Since this is a new model and the U.S. economy is changing, you would be carrying a lot more risk than if the economy were stable and the model had some history.
For roughly the same work but to reduce the risk, you might offer some build services to people, or start with an aircraft for which you could at least get all the kits and know what the price of them will be. If you're building a single airplane of a new model, a highly-integrated one, the options for making money would appear to be roughly proportional to the cost of the RV-12 kits compared to what Van's is getting for the fly-away airplane.
Also, if this is the only airplane you're going to do this with, then you'll have to figure in the cost for tools and the shop space. I bet that the hidden costs will surprise you and the ability to sell at a high price will be less than you expect. It might be worth doing a worst-case study of this to see how that looks.
I have noticed that people who have a good reputation and have made a business with RVs, tend to specialize a bit. Think Stein or Vetterman or Paul at Weep No More. They manage to stay in business. Of course, those are businesses, not hobbies.
The moral here is to treat it as a business and plan it with good business sense. It might be a good idea to refer to the rules I posted here - http://www.vansairforce.com/communit...ad.php?t=79910
for back-up plans.