While I am not a big fan of skeumorphism as a tendency in design, I think it should be used as a tool whenever needed and this is the case you should do so.
The travel cards within the app are equivalents of the physical travel cards. AFAIK, one user does not have many of them, so there should be no need to worry about how to pack 20 of them within one interface, it would rather oscillate between 2-7 cards (just my guessing, plus archive ones of course). Thus, you can go for a more skeumorphic interface, of course still keeping the graphical design within some reasonable limits.
You can see what I mean e.g. in the Passbook iOS app - screenshots here: http://www.telegraph.co.uk/technology/apple/9326872/Apple-WWDC-iOS6-Passbook-app-prepares-iPhone-to-act-as-e-wallet.html - it also regards packing multiple cards within one screen (you can see 8 within one view in this example, which is pretty good result, I think).
Regarding the details view, you could go further, and expand (also skeumorphically "pulling it out" of the "wallet"). The card could show, then, the list of transactions - scrollable if necessary.