For Mills, who has played for the Auckland Aces and just two years ago was forced to consider retiring because of a mystery back condition, it was also the moment an incredible journey from a small town in Suffolk had taken a remarkable twist.
"Never in my wildest dreams did I think something like that could happen," says the man who had entered the auction at the lowest base price of 60,000, so keen was he to get an IPL gig.
"I'd spoken with a few people and we knew there was decent interest from various teams but this was well beyond anything we thought possible.
"It's life-changing, absolutely. Provided I stay fit, I'm guaranteed 80 per cent of that money and then the last 20 is pro rata depending on how much you play.
"So that's an amazing amount and it means I can buy a house mortgage-free and help my mum and little sister out. It just sets everything up for the rest of my life."
This is for a man who, at 13, would rise at 3am to work on market stalls in Brandon before school to help his single mother who had made a new life away from her native Yorkshire.
And it is a story that could easily have had another, far less happy ending if the congenital back condition that blighted his early career had forced him out of the game, as looked distinctly possible early in 2015.
"I certainly wouldn't have thought this was possible when I was sat in the boardroom over there," he says at the Hove ground he now calls home, pointing at a small room at the top of a stand.
"Mark Robinson [then Sussex coach], Zac Toumazi, the chief exec, and doctors and physios were all there going through my situation and I was struggling to play cricket at all.
"I had such a peculiar injury that the doctors didn't really have anything to compare it with. They diagnosed it as best they could and spoke with people around the world. They laid out my options and we planned it from there."
One of those options was the dreaded "R" word.
"I've always tried to stay positive but that day in the boardroom when the word retirement was spoken was a bad one," says Mills. "I was 22 and to have that said and for that to be a possibility was not nice. They gave me time to go away and think about it. I never wanted to retire. I always wanted to give it another go.
"If the injury had come back, it might have been different but I'm happy with the option I took to play just Twenty20.
"I missed the first T20 game that year but a few days later, I played here against Gloucester and I was very nervous before bowling my first ball.
"My injury has only ever happened during a game when I've slammed my front foot down and got shocks around my waist and legs but the first ball was fine, I went on to take three wickets and it was a massive weight off my shoulders."
From there, the only way has been up, as Mills has become the epitome of the modern Twenty20 specialist, first doing well with Sussex and this winter already playing in Australia, New Zealand, Bangladesh and Dubai in the Pakistan Premier League, where he received the big news from India.
But it was three matches he played against India for England earlier this year following a promising debut against Sri Lanka last summer that brought Mills to the attention of the Indian franchises.
"[Virat] Kohli's six was definitely the best shot I've been hit for.
"India was awesome," he says. "The crowds were big and they are fanatical. It was nice to play in Bangalore, too, because that's my home ground now and it's a difficult place to bowl.
"It's a pretty small ground with a flat pitch, so you have to temper your expectations and realise you're not always going to take two for 23. The average score there is 200, I believe, so there will be times when going for 30 to 35 will be a good day."
And, in a star-studded Bangalore team that will include the likes of Chris Gayle and AB de Villiers, one of Mills' new team-mates stands out - India captain Kohli himself.
If injury had curtailed his cricket, then Mills could easily have been writing in these pages rather than appearing in them as he excelled in a sports journalism degree at the University of East London.
"I wasn't signed professionally after I did my A-levels, I was just on a summer contract at Essex, and my mum was keen for me to go to uni and get a degree.
"It was life experience as much as anything. I did my first year at UEL and turned professional the next summer. Things then really accelerated.
"I started the second year but I was away with cricket so I deferred it and then it all snowballed. I'm still grateful I did it. I got two years worth of student loans without a degree to show for it but I can pay that off now.
"I still keep my hand in writing for local papers back home. I learned the basics in that first year, so I will try to keep that going."
As the Sussex players file past us, Chris Nash, with a smile, shouts out: "There's the million-dollar man."
It is ribbing that Mills enjoys but also knows it has a serious side.
"I will try not to think of the price-tag too much when I'm in India," he says.
"I'm sure if I have a bad game, people will be all over me but I always back myself to do well."
And then, when he returns, he will go house-hunting on the Sussex coast. Daily Mail
