Since there is no official announcement from Intel, any figures stated now will be purely speculative.. However, SB processors are slated to be launched for the mainstream crowd first.. As such, you can expect a price tag range from 200$ ~ 400$..
No idea as of yet for the exact prices. Looks like we may have to wait a while for that!
I've wondered about this too, but an even bigger question for me is how long with the socket stay alive. I know we got spoiled with LGA 775, but it feels like the refreshes have been pretty quick this time around.