If-- as the artist-- you are not dependent on selling your art for income that is almost always the best way to go... especially if you have good connections to upscale galleries. Wealthy people will often pay "above market" for auction items if it's in the name of charity.

It's actually an interesting dichotomy because the very same people-- as art buyers-- are often the stingiest who'll spend an eternity haggling over a price like they were in a Moroccan flea market!