Wages are very much related to location. I know of plumbers with some years of experience who are only making $12 an hour, especially now in such a down economy.
But, if you are in an apprenticeship program, as majakdragon mentioned it is required that you be payed a certain wage dependant upon how far you are in the program.
I would want a new helper to show up on the job with a good framing hammer, a hacksaw, a torpedo level, a good tape measure, flat and Philips screwdriver, ratchet cutters, copper tubing cutters if it is a copper job, channel lock pliers, a lot of respect for what tools of mine he might use, and most importantly, a desire to learn how to do plumbing right. Some companies/foreman might have different requirments, but in my line of work, the above would get you off on the right foot.