Here is a guy in Pittsburg who seems to have beat you to it, though not by much.

http://maestroframeworks.com/blog/


It would be hard to avoid calling a frame shop something like Steel City Cycles, and making all the frames out of steel, given Pittsburgh's heritage.

I know guys who have sold their second frame. The one thing you need to focus on if you go that route is quality control, you need to come up with some means of determining that the joints you have built are going to stay together. Some familiarity with something like welding process methods, so you can come up with a means of establishing a test, and making certain that you are passing the standard, and better still how that works out in the bike. If the frame looks and works good, and you can be sure the joints are solid, then you have something to sell. The unknown is the joints. This is one place where lugs are pretty easy. First, if you do silver brazing the heat issues, which are sometime overstated, non the less, go away. Second, you can saw a lug appart and determine what penetration you got. If you managed to flow silver everywhere, that pretty much means you had enough flux, and were hot enough.

With welding it is not so easy to tell. I did come across one guys site where he had something like 100 joints he had made to learn to tig. The later ones looked nice enough, if not spectacular. He put in the time making parts, and these could be carefully examined for normal welding failure signs.

Pittsburgh and CMU did at one time have world class welding expertise. My sister worked on a project for her doctorate at CMU that had to do with weld failure in Nuke plants. You could probably find some resources there to at least get you up to speed on terminology, and make you sound more competent. Also I would quiz hard any of the folks offering courses to determine what they do to make you able to determine quality. And what follow up support they provide. Doug Fattic comes around here often, and he runs courses. And there is ANT.