AFAIK if you don't overdraft and pay on time, a credit card does cost you nothing while improving your credit score. To be fair, the score's rules sometimes seem illogical: if you take credit and returns it ahead of schedule, your credit score gets lower. That's because the banks get less money from you and they don't like it.
I have two credit cards, one is tied to a deposit the other one is a "true" credit card, both cost me nothing. Actually, I make some money when I use it. If I buy something with a "true" credit card, I have up to a month to actually transfer the money. For this time I still get interest. It's not much even if I buy something very expensive, but it's better than nothing. Besides, both cards have a cashback program: one gives 10 cents for each transaction, the other one 0,5% of the spent amount. It's not much either, but you can't expect much from cards that don't require any regular payments.
Granted, these "free" cards have horrible interest rates if you choose to take credit. Well, I'm just not doing this. I'm not buying anything I cannot easily repay.
P.S. This is Germany, US experience may vary.