PR 10's are extremely rare. That's the Holy Grail of SEO. I'd be skeptical. I think you'd be better off getting several PR7-8 links instead of 1 PR 10.
As some already have said, i would rather buy more targetted links then spend $4.5K on a single PR10 link.. I dont really see that much of a profit coming from that.
All the IVY league and other top US .edu have PR9+ $4500 won't be too big of a deal for few ppl(read as companies) who are in financing(mortgage) or similar businesses. It depends on who needs it for what purpose. $4500 for PR10 is not costly since only handful of pages on net have them and they are considered to be "ultimate" (though I have seen a guy selling PR 15 link on DP, but that's a different story altogether)
well well well i would go with the rest and keep my money, i just dont know why there are so many con acts out there be careful that is all that i can say..... save your cash and do it the old way it does take time but you will get there in the end this game is a long road