I think Birdstone is crazy good value at 10 grand.
You are talking about a horse with all the things you look for in a sire.
He won early and fast in his debut at age two.
He won fast at a mile in a grade one at two.
He won at a mile and a half in a classic at age three
He won at a mile and a quarter in a grade one at age three.

I know the knocks on Grindstone, but he occasionally sires fast horses. And his mare also produced an Oaks winner in Bird Town which shows me that he wasn't just a fluke production by the mare.
Don't be surprised if he sires some damn good runners and soars in price before hes all done.