I see, so the concern is that checks would bounce. Our policy is to wait for checks to clear, before processing the order. Does that solve the problem, or are there other concerns?
Waiting for the check to clear almost solves it. But how much does your bank charge you when a check bounces? Maybe you should have a minimum buy-in for checks. Like they have to fund an account with $25 or $50 dollars. At least that way the NSF fees will be offset by the people who fund accounts but never use the money.
Yes, our bank does charge us for bounced checks. That is a good point. So far, we get many more credit card chargebacks and Paypal reversals than bounced checks.
If we get Paypal reversals or credit card chargebacks, then there is not much we can do. It is part of running a business that sometimes people will try to cheat you. We consider it a business expense.
We do have fraud filters to try to limit the fraud we get.