Screenshot of BP5 for VS MarvelTM showing Deck Stats
I was planning to make an Access database...but then I found Battle Planner.
It's pretty cool. It won't track the value of your collection, but it does just about everything else. It's only $20 for the full version, and it'll keep an inventory of lots of games. (It would have cost me way more than $20 worth of time to do as good of an Access DB.)
I'd definitely recommend it.
--"infallible", WizKids Forum