You could take a fresh look at how custom handmade frames are distributed.
Anyone who fully commits to anything for a business runs into a few inherent problems, such as possible bankrupcy if the business fails and high unit cost due to the necessity to make a wage.
That said, I believe if you do get the tools/workshop/jigs in place and do it on the side at the start, you could post a design or several designs on ebay and LBSs and make frames to order.
Taking for granted you have a day job, you can do frames on the side till you bust through a threshold, if it comes, then go fulltime frames.
Baum make a wonderful carbon titanium bike (Ristretti Ti) that weighs in under 7kg without pedals and when teamed with the top of the line campy groupset, will cost well over 10k. Now joe average only wants to spend 1/10 of that.
Having a frame handmade and indiviually numbered would be a dreamy thing to have, and if you could knock one up in a couple of weekends for like, 1k, then let the legend spread.
Other than the risks involved in any business, I'd encourage you to give it a go, even if its part time...