I really haven't bothered with Listia much. There has been way too much stuff I've had absolutely no interest in adding. I won't shell out credits for an address for TTM for Ryan Braun. Or for a picture I can find through Google images. So, if I see something of interest, I just put in my total credits and hope to run out of them at some point.
I've still got way too many, but these two cards put a nice dent in them.
And even with this I still have 1900 credits to blow. Anybody want to get into a bidding war with me on a Pro Set Mike Vernon?