Well, first of all, AMD stated that the FX series of processors will still remain their top of the line cores, therefore you can reach the conclusion that the Toledo core will cost less than the Sledgehammer (?) cores.
Also, based on it's near identical specifications to the 4000+, however, it's more efficent and cost effective 90nm process, it should come out cheaper than the 4000+.
Basing my estimate on the leaked benchmarks that came out a while ago, which show the Toledo outperforming the 3800+ but still being outdone by the 4000+, I'm taking a guess and suggesting that the price of the Toledo will be about the same price as the 3800+ is right now, pending its release date. $300-500 is my guess.
I'm curious, based on the fact that it is two cores, can you overclock one core yet keep the other core stock speeds, or adjust them to run at seperate speeds. That'd be pretty cool in my opinion.