Here are some marbles. I haven't ordered from this site yet, but they have quite a few colors.
http://quilthome.com/index.php/cPath...sort/2a/page/1
As far as credit card goes, some places will take PayPal, which you can set up to pull from your checking account. I use PayPal all the time. There is no charge to use it. You could also ask if they'd take a check by phone. They will likely hold your order till it clears, but it's an option.