Are you able to pay off the card purchase? Most of the cards that give you a small rebate have such high interest rates on balances that you would lose that small rebate in one or two months just due to the high rates.
I use my Costco Amex card and get a small rebate, but the balance is paid automatically every month. If I needed to finance something really necessary (A new camera isn't), I'd do it thru my credit union.