I think its worth noting that a lot of builders want to do it themselves, After all, thats what we do for fun and enjoyment. Depending on your plans, if you offer any options you'll probably get bombarded with special requests. Sounds like a good way to use up ALL of your spare time.
If I was building them, I would consider putting each one up for auction when it was done. That way you don't have to deal with orders, backlog, special requests, etc.... You'll also get to judge the market by the interest you see in bidding.
Good Luck, however your plans work out...