[tghw]

Yes, if you're giving enough that the credit card fees are substantial, then you should be using another payment method. At worst, mail them a check. There's nothing better for a small non-profit than to open a letter containing a large and unexpected donation check.

[zachlatta]

In my experience, most people making gifts >$25,000 are either making them through a foundation or through a donor-advised fund, both of which almost always write checks.