I'm in the same boat as you. I got into welding and metal fabrication because I was big into cars, and I wanted to build my own Improved Touring Class C road race car. I made some exhausts, etc. But the car thing proved to be too expensive, and time consuming... stripping the car (CRX), building a cage, rebuiling engine, on and on...
So I'm looking to get into frame building. Steel frames. Been compiling some good bookmarks on the subject. Can anyone recommend a good first book on the topic? The Paternak book is $75... a bit pricey.
I think for my first frame, I'll use my MIG welder to tac the tubing in place, and then take the frame to a good weldor for final TIG welding. Or I'll learn to braze, and use Lugs. Not sure yet.