Agreed with Boats it would be nice to get donor status without the EP. Finishing every single achievement could land you at 100 or even 250 total donated, it's A LOT to do.
Rewards could be total donated to account per each set completed (Combat I, Combat II, Combat III, etc) and Achievement Reward Boxes awarded after completing each block of the set (Easy, Med, Hard, Elite). The number of boxes you get should depend on the difficulty of the block. I think it could be 3, 6, 9, 12 for each difficulty. Personally I think the reward boxes should be tradeable depending on the contents.
There could be a cosmetic set that is unlocked where each General, Combat, Skilling and Minigames give you 1/4th of the outfit (Maybe a Master Questcape as the 5th item if you do every achievement and complete all quests)
Potential Achivement Reward Box Contents (rarity by color)
Gold
SoF Spins
Crystal Keys
Agility Tickets
Clue Caskets
Vote Tickets
T 1-3 Well Ticket (A ticket to add 250, 500 or 1b to the well)
Rare Cosmetics (SoF, Seasonal, Achievements Specific?)
Insta Kill Darts