So funny guys, Paypal have NEVER EVER supported DONATE X for ITEM Y. Ok, never. THis is what you can do to win every chargeback.
1. STOP calling it a DONATION. If you call it a donation it's very easy to win. Just say you regreat that you DONATED.
2. Only allow vertified accounts, they are much safer.
3. If they chargeback then you send a nice likes to your own terms (they doesn't read them, it just looks more pro), and to paypals terms that clearly states that virtual goods are not covered. Also send a image of your log that states that the payment falled trough.
Ok, follow these 3 steps and you'll never loose it.
I would try moneybooker and my first impression sucks. It took them 3 hours just to send the vertification email, by then I had tried to reregister 3 times with diffrent email, and I signed up, got vertified (i believe i did atleast) and made a fully working system for AlertPay (just a "quick" solution tho).