there are baseball cards that go for insane amounts of money http://sports.gunaxin.com/most-valueable-baseball-cards/195571
It does take a while, I will warn you, and on popular games, it almost never happens. I have been getting trading cards for three years, I have around 80 games, not a single one has given me another drop.
I know, it really sucks. I like keeping my cards and collecting sets, but I just can't justify buying cards, even if I made money from selling cards.
I occasionally buy pokemon cards. I somehow got this card in a booster pack: https://drive.google.com/open?id=1wTiwsskUz3zpUsThJB_UE_y7EkJ7frvOBg
Pigeon FTW! Says it's worth $38.46... Return investment Im kidding, this is the only game that I'll actually KEEP the cards. But dang, 700 hours of Beam and I'm just now getting rewarded, better clock some more hours. ---Post Updated--- Already got 3 Gonna wait for more to be sold so I can finish my deck at a lower price --- Post updated --- Count me in! I love nefarious plans.