Banzai-
I'm not sure why you would think that the DCA Monorail, with Golden Gate Bridge, would be available at WDW. On the other hand, it wouldn't surprise me... In July at the World of Disney in Anaheim, the had a whole side of a pin kiosk with nothing but WDW pins!
In May, WDW was still selling the WDW Monorail version.
The trains do not "eat" batteries like some electronic cameras I know of, but if you want the Monorail to run around a Christmas tree for hours at a time, be prepared with extra batteries on hand.
You cound probably find one of the DCA Monorails on eBay at a decent price, check it out. I think the park was selling them for $65.00.