Not that I'll be buying anything other than a 2500k, but there has been NO change, that I can see, on the price of any AMD or Intel CPU's with the release of SB. The Egg has the i5-760 still pegged at $205. The top of the line AMD hex core is still at $270.
SB 2500k is looking more and more like "the bargain chip".
Right now SB is the best bargain since its priced very well.
But the others will drop in price. It will just take time. Its not an instant drop Probably within the next month or so you will see lower prices for Phenom II and possibly older LGA1156 CPUs. Maybe even LGA1366 will drop since SB does tend to make it look sorta bad. Not really.
But yea. Give it time. Or just buy Sandy Bridge. Can't go wrong there.