Don't be too quick to jettison the notion of a good apprenticeship program.
The good ones (if you can get in one) will start you out somewhere near $20 per hour full time with full benefits. You will work and go to school at the same time (school paid for by the union) and you will learn much more than just fitting.
There are others here who can also attest to the thorough learning that comes from a good Steamfitter, Boilermaker, Ironworker, Pipefitter, style apprenticeship.
How much experience do you need? That is going to vary quite a bit on the type of work you apply for.