Black Caviar's half sister has been sold for $2.6m to Melbourne bloodstock group BC3 Thoroughbreds, and will be trained by Danny O'Brien.

The Redoute's Choice   daughter of Helsinge was lot number 200 at the Inglis Easter Yearling Sale and BC3 Thoroughbreds prevailed in an expensive bidding war.

“At $2.5million I got a little bit wobbly," BC3's Bill Vlahos said.

"We pretty much stuck to our price and we think she is worth exactly what we paid for her. Too much more and it might not be us owning her but it is exactly what I think she is worth and hopefully more at the end of her racing career.”

Black Caviar  's trainer Peter Moody was also bidding for the horse but bowed out as the filly's value skyrocketed.

Katsumi Yoshida is believed to have been the second big bidder, with his last offer at the $2.5m mark.

Yoshida bought a share of Mosheen   before the autumn.

The filly will be under the care of Danny O'Brien who is understandably thrilled about training such an exciting racing prospect.

“It is very rare that a horse like this is offered for auction,” O'Brien said.

“Fillies like this generally would be retained by breeders, anyone lucky enough to breed a filly like this would be loathed to sell here.

“It was really a once in a generation chance to buy a filly like this. She is an outstanding individual herself and the mare [Helsinge] is still a very young mare, this is only her fourth foal.

“She has shown us what an outstanding producer she has been with the three foals that have already raced and this is arguably one of the best stallions she has been to.”

A sales price of $2.6million will appear less extravagant if her half brother All Too Hard   can bolster the families black type when contesting Saturday's Group 1 Sires Produce Stakes (1400m) at Randwick.

“Hopefully she will be a half sister to another Group 1 winner on Saturday," O'Brien said.

"She is probably going the way of similar mares like Eight Carat who have produced the four and five Group 1 winners.

“Hopefully we'll look back on this day and say that we were lucky to get involved and bought ourselves into a generation of fantastic Thoroughbreds."

“She is a filly you would not even generally get to buy. For whatever reason Rick has decided to sell and I spoke to him the other night and he said that he did not think there would ever be another horse out of this mare that would come onto the market,” O'Brien said.

“We are not going to be able to buy Black Caviar and certainly not buy All Too Hard  , so this is the last opportunity. Everyone who has looked at her has been very positive and we certainly could not fault her.

O'Brien said that he had started inspecting the filly once she had reached the sale grounds early last week.

“I said to Bill that anywhere between $2m to $3m and the closer you got to it, the more you realised that it was going to be closer to the $3m, so I think that is probably about par. It is a lot of money, but as I said of Black Caviar herself what price would you put on her, and the colt with his stallion potential is well north of $20m if he wins on Saturday.

“So she is a filly from the best family now as close as she is to Black Caviar and you have a long time to get your money back. She does not have to come out and win the Slipper for us to get square.

“We have got a long process now where we can be involved with this filly. I would suspect there will be a lot of horses here that will make a lot less money that will have a lot greater risk money put into them.

“I would suspect she will have a similar programme to her half-sister. I would not expect that she would be up and in the two-year-old system. We would be expecting that if she did race it would be more in line with Black Caviar than All Too Hard. Black Caviar herself, I think, only raced six or seven times before she turned four and naturally we will not be doing anything in a rush until the filly really needs to get there