You should be fine. Paypal explicitly allows the donate button for tips and things, even for non-non-profits (is that a word?). The root issue here as far as I

You should be fine. Paypal explicitly allows the donate button for tips and things, even for non-non-profits (is that a word?). The root issue here as far as I can tell is that regretsy is promising some kind of action (in this case buying a "mystery gift" for an unknown family) and Paypal has no way to verify that this is actually happening. You are fine as long as you don't explicitly promise something. There's no way to claim you are running a fraudulent service if the money is out of goodwill for no purpose. There will be very few chargebacks to Paypal that claim "I gave jfruh a tip for nothing in particular, and he used it for something in particular."