Along the same lines as what was brought up, he's got to have something else going on other than just not wanting to accept checks. While I do agree your accountant should be fine with the receipt, the web designer should not have an issue taking checks from you, especially since you've been a loyal customer. As a WebDev myself, I have no issues taking check payments from customers (I live in Houston so face to face meet ups aren't all that common after the first few meetings).