Several Palm Pre accessories landed in Best Buy's internal stocking system today, and according to PreThinking, the "Touchstone" inductive charger kit will cost a whopping $69.99 for the charger and the replacement battery cover to make it work.
According to this image from PreThinking, Best Buy is stocking three acrylic cases, one leather case, one case labeled 'Palm Pre Case" and the "TouchStone Kit." All are listed as being in stock on May 10, which was yesterday.
The Touchstone charging dock uses magnets to align your phone in the correct position for charging, and allows you to use your phone while it's charging. If you set your Palm phone on the dock when making a call, the speakerphone automatically comes on. Take a ringing phone off the dock, and your Palm phone answers the call. The accessory requires a special (metal) back cover to work, as the Pre will ship with a plastic back cover.
The site also says "the chances of a mid-May release is looking very dim," and June 7 would be a likely Pre release date.