A staples ad confirms that the wifi only silver xoom will be $599. I think sams club might have it for $539.
WiFi-only Silver-Backed Xoom: $599 at Staples, March 27 Release Date [Updated] - xda-developers via WiFi-only Motorola XOOM Priced $599 at Staples - Droid Life: A Droid Community Blog
WiFi-only Silver-Backed Xoom: $599 at Staples, March 27 Release Date [Updated] - xda-developers via WiFi-only Motorola XOOM Priced $599 at Staples - Droid Life: A Droid Community Blog