Sell whatever you want for whatever you want.
Wishes I could find a crimson for 10M, then I would just need to find the 10M!
Seriously though if you are having fun, heck with what others are saying.
Me? I sell treasure maps really low - level 6 maps I sell for 1500 and prices go down from there. Many people have asked me why? Easy, I have no use for them, I do not have a treasure hunter, never wanted one. So I would rather people that do treasure hunts get use out of the ones I find.
I used to donate maps to guild I belonged to but, I am not in a guild currently.
And at one point, I had a RL friend who loved to treasure hunt (more power too him), I worked it out that he could have everyone I got for free, I just wanted all the gems from them. It worked out fine. But he quit sometime back, so fast forward to today where I sell them for very little.
To each his own. Its the greatest strength of UO, the sandbox style of play.