This is an odd request, but something that I would be interested in seeing:
What about busts of characters?
It seems a fairly common miniature to paint, even if it is not for gaming purposes. A lot of prominent painters have done some really spectacular things painting a bust. I'm not sure if it would be smart to do it in metal because of the size, but if possible I think it would catch the eye of a lot of enthusiasts -- even those outside of BattleTech.
My recommendation would be to do a bust of Natasha Kerensky. Even better if it could be based off of the CCG art.
Again, I don't know if this is possible. It may or may not need to be done in plastic or resin rather than metal because of the sheer size. That being said, the cost is probably not that much of an issue. Many busts seems to range between $45 to $65. The museum scale sculpts are already that much. If anything, it may be more difficult to find the sculptor willing to do the work.