Mr. Cards is fantastic for two reasons: 1) the owner is cool, and he 2) sells cards cheaper than anywhere else I've ever seen.
If you're looking for old sports cards or esoteric comics, this place is not for you, but if you are looking to spend $15 and play Magic: The Gathering on a Friday night instead of spending $35 + tip, getting plastered and nursing a hangover the next day, then this is the place for you.
(no witicisms on this one, I've just outted myself by reviewing it!)