Rather than having one prestige mission a day, which is based on the level of the character, have say 5, with various donation levels and prestige rewards. Either have them all unlocked but only allow one to be completed per day or only unlock the higher levels after the lower donation is made.

This would allow players to "donate", at a level they feel comfortable with, some players will not be willing to donated 2,3,4,5* items, and the current system prices them out of the prestige market, after they rank to much.