Steam cards

maybe at the beggining, the cards market suffered a crash after the summer sales and the prices are too low to do anything of the sort now.

But most sell for an insignificant amount (less than a dime). You would need more valuable cards, unlocked while you play.

So what do people do with their leftover cards, for example do they finish their sets (by trading other cards) or is it possible to finish sets without even trading cards sometimes o.o?

Greenlight games I've gotten for cheap or in bundles have payed themselves off. If you get cards as soon as they are released you can make money back as the first few sell high.
Signal Ops, Bionic Dues, and Mousecraft spring to mind.
I dont even own Bionic Dues, but I traded at steam card exchange and sold the backgrounds/emotes that I crafted for far more than what the cards were worth.

hmm,tyty for all the input.

It has happened before, Groupees Build a Doujin Bundle with Cherry Tree High Comedy Club, Ether Vapor Remaster, and Satazius.

And again with the Capsule Computers $1 Bundle (Cognition and Super Sanctum TD).

Though card prices overall tend to keep dropping, so the likelihood of it happening decreases all the time.

You'd struggle to make the whole $1 back unless it was a particularly good bundle with a few trading card games in there that sell at decent prices, but it's not completely impossible. I think the best you can really hope for is that it will pay some of it off. More often than not I'll get at least 25% of it back if not more than 50%. Besides, it's Steam wallet funds so it's not like it's real money such as the real money you have to use to buy bundles.

seems like bundle games are good games to powerlevel/craft your steam account on though