Have you considered using PayPal as a way of receiving payment from Internet users? It lets us send e-money using email without needing to go dig out our credit cards and play games with the numbers. All you have to do is click on the emailed link to recieve payment and the money is moved right from the buyers checking account (or credit card account) into your checking account.
I see this used a lot on eBay to transfer money so I registered with them (no charge) and found it to be a great service. It would make it much easier to order on a whim while using Mudcat.