We've got bad news for these eBay sellers -- a poster on NeoGAF noticed that Marvel vs. Capcom 2 has been rated for both the PS3 and Xbox 360. Presumably, the title will be a downloadable one on the PS Store and XBLA. The ESRB has been a good source of leaks in the past, so we have no reason believe otherwise in this instance.
With the a total of 56 playable characters in the game spanning two vast fictional universes, hopefully Capcom doesn't plan on charging us $1.99 per character download.