Current best price for Aliens Colonial Marines?

You can get $2.14 (as in, you get $2.14 after fees) from each key (and they sell pretty quickly), so you only need 24 of them. If you buy them at $1.30 each (which isn't too unreasonable), it'll cost you $31.20, and you'll have a $1.37 over in your Steam wallet.

If you have the time to search/trade and don't mind researching prices a bit, you can probably get it for a bit less than that (as in ~$28), but that's probably not worth the time for most people.

Still, buying TF2 keys and then selling them on the market is a really fast and easy way to get more out of Steam (but it only works for things on Steam, of course). Just be careful not to get scammed; check out the people you're trading with, and get a trusted middleman if you're unsure.

Thanks I bought it using the code! =)