I have made my living off Ebay for the past 2 years. I don't seem to be getting rich but it is enough to survive. I have two girls age 2 & 6 and it is awesome how much time I can spend with them.
About 1% of what I sell is cards and I probably lose money on that. I sell mostly Board Games, Toys & Kids books. I purchase nearly everything from thrift stores. On average I make 9 times what I spend on an item (after fees). Making a 900% return is insane but it takes a lot of $3 purchases to amount to much.
I am limited by the fact that the thrift stores only have so much. It doesn't matter how much capital I have, if I have nothing to buy. I have gotten pretty organized but I have a considerable amount of space taken up by merchandise.