Well, one way thats good is Paypal. Well, you need a CC for the money to be stored in there >.>
Also I'm not to sure because I am Australia but can't you still get Counter-Strike:Source or whatever game that you would like at an EBGames or a GameStop or something like that I have been told, and since they are a retail store they take cash so maybe you should enquire into that.
I agree with the pre-paid credit card idea.
how would i go about doing the pre paid credit card thing?
Head over to your bank, and ask them about it.
Go to wal mart get a prepaid card or to a bank they have them just have to pay like a small fee, but if you know someone really well that has a CC have them buy the game you can just send them the money.