Speaking only for myself, I don't mind custom orders when they will be a vehicle for moving my art forward. I recently accepted a commission for four very unusual pieces, primarily because I enjoy a challenge and it would take me in a direction (artistically) that I'd been too busy (lazy) to go on my own. LOL!
The price would depend upon who was doing the work.
I found your post VERY interesting, as one of the new directions I've been going with my work is architectural lampwork... Fixtures, tiles, knobs... In fact, I just got the stuff I needed to make a fan pull for my own use. If I ever get around to it. LOL!
Good luck!