But NZ Bloodstock's Andrew Seabrook said there was nothing exclusive about the sales.
Even if people were not interested in horses it was worthwhile visiting the 12ha complex to soak up the "fantastic" atmosphere, he said.
The sales auditorium has capacity for 1100 people.
"Once people get in that ring and watch horses being sold for up to $1 million, it's quite gripping and they get quite hooked on it," Mr Seabrook said.
"There's no cost, you don't have to book - you just turn up, go and grab a seat, and watch the horses being sold."
About 80 per cent of NZ Bloodstock's auction turnover will be generated this week, and it works hard to make sure buyers attend.
Top buyers are taken around town in a fleet of luxury vehicles driven by holidaying police officers.
And a full hospitality service lets overseas buyers in a single phone call arrange their travel, hotel, register as a buyer, set up an account, insure horses and get them flown home.
"Most of these horses are about 18 months old ... so the Asians and some of the Australians will leave them here on our good grass, they'll be broken in and prepared here," Mr Seabrook said.
NZ Bloodstock has its own air freight department for when such horses are ready to be sent overseas.
"They'll go in a horse plane, or sometimes you might be surprised, they'll go in the back of one of your passenger airlines when you're going across the Tasman."
Mr Seabrook said anybody paying a first-time visit to the sales this week should not mistake the social atmosphere for one of frivolity.
Before auctions buyers study a yearling's pedigree, how its relatives have performed in the past, inspect the horse numerous times and have a vet examine x-rays to look for potential problems.
Phar Lap was sold at the national yearling sales in 1928.
"The beautiful thing is a horse that goes through the ring for only a few thousand has a chance at being an absolute champion," he said.
Kiwi horses keep buyers coming back to Karaka
Pioneering Singaporean liver surgeon Dr Tan Kai Chah expects to buy three or four yearlings at this year's sales.
The Malaysian-born racing enthusiast has been coming to Karaka for the past eight years and said New Zealand horses were a sound investment.
Dr Tan and other international buyers from Australia, Singapore, Japan, Macau and Malaysia will account for about 65 per cent of sales this week.
"Last year when I was here, we bought four, and we have been very, very happy with them," Dr Tan said.
The best of them was Gobi Ranger, bought for $75,000, and second-favourite for last night's Karaka Million race at Ellerslie.
"By and large, most of the horses do well for us, because the prize money in Singapore is pretty good.
"So if we are buying horses in the range of $50,000 to $150,000, by and large you would get your money back."
Dr Tan said he had a good idea of what horses he might bid on this week.
Races in Singapore were shorter and so speed was favoured over staying power.
But final decisions could not be made on paper, he said.
"Sometimes when you see them they are badly upset, or they are not the size that you want, and suchlike."
He said it was always a pleasure to visit New Zealand.
"At this time of year the weather is very, very good. The food is very, very good ... Normally I come here for the sales, and then a week before or after have a short break."
National yearling sales
*1492 thoroughbred yearlings auctioned across seven days of selling until next Monday.
*Total turnover at last year's sales was more than $77 million.
*Buyers come from Australia, Hong Kong, Japan, Macau, Malaysia, Netherlands, Singapore, South Africa, UK and Ireland and North America.
*Last year NZ Bloodstocks had 340 hotel rooms booked across Auckland for a total of 1711 room nights.
*For the past four years, Euro Restaurant has recorded a sales increase of 20 per cent during the sales.
*Legendary industry figures like Bart Cummings will attend, as well as reps of United Arab Emirates vice-president Sheikh Mohammed bin Rashid Al Maktoum.
*The leading domestic buyer for the past seven years in a row, David Ellis of Te Akau Stud, purchased 31 yearlings for a total of $6,487,500 last year.
*The premier sale, on Monday and Tuesday, last year grossed $54 million, with a sale average of $155,000.
*The largest market is Australia, whose buyers spent $32,757,000 last year.
*$3.6 million was paid for Don Eduardo in 2000, the highest-priced yearling ever sold at auction in the Southern Hemisphere.
