"We accept wire transfer, money orders, certified checks, company and personal checks, Master Card, and Visa. Due to the low mark-up on wholesale orders, we have a 2.5% surcharge on Master Card and Visa orders. Wire transfers and checks never have a surcharge when you order from us. Remember personal and business checks have a 3-day hold."
Imposing a surcharge on VISA/Mastercard orders is a violation of their terms of service as a merchant. Wire transfers AND certified checks are also irreversible transactions. You're more likely to choose the latter over the former...so what I would do is, RUN, RUN, RUN.