Well, lets take an example from /sponsor. One player donates his cash, but it must be distributed equally among all players. Instead of rewarding the donator, how about we reward the entire community? Some things that jump to mind scream supporting our development team in one way or another, or to vote priority of something on the roadmap for say a week. Want to see Fishing? Donate $20USD and buy 5 days for the dev team to focus on that project. Arbitrary numbers of course. Pay to win could potentially be the death of the server, and it's a touchy subject to even bring it up.
If the intention is donations required to keep the server alive, then reward all the players, not the donator. I don't even expect a thank you anymore when I /sponsor, but I still do; because I love this place and want to see the playerbase stay. Another example: if we meet a preset donation amount for the month, then the entire server can use neons for a week. Or get trucking back in the server and to hell with this /mine skills for now. Even a simple storage for guns inside a house for the whole server would get people donating. The players aren't here cuz SA:MP has the best graphics, or is the latest and greatest. The players stay because of a loyalty to the community as a whole, and the idea of what Argonath should be. Promises were made about updates, and some have been met, others have not, HQ's got its own re-structuring going on, and devs have a huge workload.
If we're going for donations, lets make it a team effort. EVERYBODY benefits, just like /sponsor, whether youve been idle for 12hrs or just sponsored 50k yourself.