I'd consider UMvC3 pretty fairly priced. 12 new characters and a new mode. Of course, I never bought regular MvC3. Even my beloved Guilty Gear makes very minor revisions. GGXX->#Reload only added Robo Ky (and lost Clone Rky.) #Slash had more significant revisions and I think added Order Sol. Accent Core added ABA and significant changes like Force Breaks. Accent Core+ added modes and secret characters back into Accent Core. The thing is, none of these added more than one character.
...Which is actually why I'm hyped for GGXXX. We should get at least 4 new characters, if it ever gets made!
--
The tragedy continues!