[shousper]

Agreed. I wonder if you could put a clause in your terms of service that states you will not give refunds for modified price amounts?

Then on your confirmation page, just have a nice "Thank you for your donation. Unfortunately, you won't be receiving any goods. Please see our TOS for details."

Probably illegal though >_>

[blcArmadillo]

One issue with this, besides the possible legality of it, is if they used their credit card they could just dispute the claim. Stripe for example charges you $15 anytime someone disputes one of your charges even if you didn't do anything wrong. So you'd probably end up being out more than if you just refunded the money. Not sure what PayPal, Google checkout, etc policies are on this although I'd imagine they're quite similar.

[pbreit]

I'm not sure putting this in your terms is illegal but tampering with the amounts like that certainly is.

[brntn]

Also asking for trouble with PayPal. Which we all know can cause small stores a world of hurt.