Brian, I am sure that what you said is very true about the time and cost to make the extensions, especially in low quantities. However, if someone on ebay can sell a cornflake that looks like the state of Illinois for $1500, then I'm sure your little part might bring a reasonable reward.

Just call it an exclusive piece, a one of a kind, and start the bidding at a ridiculous amount, like maybe $300 and see where it goes. Might help if you could see the likeness of a well known landmark or a Holy Diety in the inside boring.
Oh, and it may go faster if you offer free shipping. Everybody loves a shipping bargain.