The register has a quote from Nintendo saying it will be out in the U.S. by Thanksgiving, and hinting that it will be a lot cheaper than the 360 "Even if it's a superb machine, it's not going to sell if it's ¥50,000 (£246/$433). We plan to make [Revolution] an affordable price."
MKy guess would be "affordable" in that context probably means sub £200/$300 (and hopefully sub £150)