How much do you reckon it costs for the upkeep of a koi pond? Ditto separate wet and dry saunas, an elevator, and tending to manicured rose gardens?
These are questions that Harry and Meghan, the Duke and Duchess of Sussex, may well be in a position to answer as the owners of a Californian estate that boasts not only these features but also 13 full bathrooms, a cinema, a games room and a Japanese-style tea house next to the pond. Namaste.
Absconding from royal life, it turns out, comes with a steep price tag, quite literally.
But now, in an interesting Sliding Doors-esque revelation, it has emerged that the renegade couple had been slated to ultimately move into one of the royal family's most famous residences, had they not hightailed it out of the UK. (And with not a bill for a koi pond in sight.)
This weekend, the Mail on Sunday reported that a "radical" overhaul of the royal family's living arrangements is planned after Prince Charles becomes king, including that he will eschew moving into Buckingham Palace's "lavish living quarters" and that the monarch's private apartment will "be reduced to little more than a flat above the shop."
The notion that King Charles III will likely not inhabit the 318-year-old palace is not a new one, but it is worth paying attention to the details of what will happen to the rest of the royal family's vast property portfolio of homes, both those they own personally (such as Sandringham and Balmoral) and those owned by the Crown (such as Windsor Castle).
Turns out Harry and Meghan, under the plan, had previously been pegged to move into Clarence House, a vast property. Wildly speculative estimates have put its worth at more than $100 million.
The Mail reports that "in London, Charles's official Clarence House residence was originally earmarked for Harry", but his departure to California means that is "no longer on the cards".
"It is now more likely to be saved for Prince George, Princess Charlotte or Prince Louis."
(The report also states the property's "outdated decor is a turn-off for younger royals" but that's nothing the Sussexes couldn't have sorted out by installing a battalion of greige sofas, plenty of Diptyque candles and saging the place to get rid of the ghost of the Queen Mother bumping into her drinks cart.)
While it may not be the biggest home (it's hard to beat Buckingham Palace's 775 rooms), the symbolism of Harry and Meghan and their family moving into Clarence House would have been significant given its sterling royal pedigree.
Sitting on The Mall, less than 500m from Buckingham Palace, the Georgian pile was where the then-Princess Elizabeth and the Duke of Edinburgh lived after their marriage (and before her ascension). Princess Anne was born there and then later, famously, it was the Queen Mother's home for nearly five decades.
When she passed away in 2002, it became Charles' official London residence and it is where he has greeted foreign heads of state, including former US president Donald Trump.
It was also the location from which William and Kate, now the Duke and Duchess of Cambridge, gave their engagement TV interview in 2010.
This Clarence House news raises an interesting point, namely the list of glittering, money-can't-buy perks the Sussexes (and their children) would have enjoyed if they had not decided to huffily call it quits.
Take the new royal yacht. Earlier this year, British Prime Minister Boris Johnson announced plans to replace the Royal Yacht Britannia, to a resounding chorus of "huhs?".
Buckingham Palace quickly let it be known it had no interest in this very expensive, floating PR-disaster-in-the-making, with a source telling the Times: "Charles doesn't want it. William has no interest in it."
Still, Johnson has ploughed on, and the £250 million tinnie will set sail and be in operation by 2025, according to the Telegraph, at which point the royal family will be in a position to use the floating gin palace for official business.
Even before it's out of the slipway, the flagship vessel will immediately become the most exclusive yacht in the world.
Had Harry and Meghan stayed in the royal fold, they too would likely have been able to use the 125-metre behemoth when they were out and about representing Her Majesty.
No matter how many times Jeff Bezos or Roman Abramovich might lend the Sussexes' their seafaring monstrosities, nothing will quite compete with the prestige of getting to set foot on this addition to the British naval fleet.
Likewise, there is the jewellery situation.
One of the great unknowns about the house of Windsor is just how vast their collection of glittering gems actually is, given it comprises (as with their properties) both pieces owned privately by the family and those which belong to the Crown. (Only a small selection of the most historically important pieces are on display at the Tower of London.)
The Queen lends pieces to female members of the royal family on a lifelong basis with the understanding that no one else is allowed to wear them.
She regularly dolls out more pieces in recognition for hard work - for example, when the Queen lent Kate the Bahrain Diamond and Pearl Drop earrings (which had been given to Her Majesty for her wedding) to wear to the Duke of Edinburgh's funeral in April.
We will never know which sparklers the 95-year-old monarch might have planned to lend to the Duchess of Sussex.
While Meghan inherited a number of pieces that belonged to Diana, Princess of Wales, including diamond butterfly earrings, a stonking aquamarine ring (and likely the matching bracelet), and a gold Cartier watch, it is highly unlikely, if not nigh impossible, she will ever be given access to this trove of priceless pieces.
After staging her drama-filled exit, that royal collection may very well be off-limits to Meghan.
But what of the Crown's art collection, which is said to be among one of the biggest in the world? Why, I'm glad you asked.
Members of the royal family are allowed to borrow pieces from the 7,500 piece collection, which includes Old Masters, for their walls.
In 2016, William and Kate made headlines when Barack and Michelle Obama visited them at their Kensington Palace apartment and official photos revealed that one of the pieces they had chosen from the collection was a 17th-century Dutch painting known as The Negro Page.
Again, dipping into this Aladdin's Cave of artwork is now off the table for Harry and Meghan.
Then there is the question of the, potentially, tens of millions of pounds they walked away from.
Prior to Megxit, the couple's personal expenses – yoga mats, organic hummus and the like – were footed by Prince Charles via his Duchy of Cornwall estate to the tune of about $4.6 million annually.
While Prince William will inherit the Duchy of Cornwall when Charles ascends to the throne and he assumes the title of the Prince of Wales, it seems improbable that the new king would have, in this scenario, suddenly cut his younger son off and forced him to fend for himself.
In fact, as King, Charles will have access to the Duchy of Lancaster, which is valued at more than $1 billion and pulled in $45 million in revenue in 2020.
Which is to say, even when the inevitable shake-up happens at Buckingham Palace, had Harry and Meghan stayed put and not flounced off to learn how to live authentic lives and borrow private jets, this sort of financial support would have continued.
Talk about money for jam.
Sure, in this scenario the duke and duchess would have nothing like the estimated $180 million plus they will reportedly earn via their various commercial ventures. However, neither would they have found themselves lumped with having to find the cash to fund their luxurious lifestyle.
According to Debretts, "Money is the oil that greases the wheels of society but oil is filthy sticky stuff and we should clean our hands of it before coming out in polite company."
Quite, but that's easy to say for someone who doesn't have to find the dough to keep a koi pond running for the rest of their lives.