I totally agree with Klaus, if that is the way you want to go. I also charge $50.00 per hour, though I now charge $75.00 in the C-340A and have no problem getting it, but that is really well under what many other instructors get, I.E. Ski, Tennis, Scuba, Golf etc. Most charge $75.00 to $100.00 in this neck of the woods. If you work for an FBO though, expect them to take part of it, so you may net $40.00. Again, weather is one of the factors that will determine how much you can really make, though now a days with the level of sophistication that some simulators have, you can make billable time lost from weather in the simulator.
In the late 80s I owned and ran a Multi-Engine Training School in the suburbs of Chicago (I was there part time as I had a real job). I had three Duchess's, two C-310s (one Turbo), a C-421 and a Sweringer Metro Liner. So basic Multi through Turbo Prop / High Altitude / Pressurized. Chicago can have some nasty weather. So, I bought a Frasca Multi Simulator. At $80,000 this advanced model cost more than all but the 421 and the Metro Liner, but it made me and all my CFMEIs very happy. Much of our Part 141 Multi-Package could be practiced on the ground when the snow was coming down in blizzard conditions. To get instructors, I gave them free time to get their ratings, though I did not make them sign a contract. I did allow them to rent for personal use at cost, which helped them build more real Multi-PIC time so I did not have a huge turn over.
Still, most of these full time CFIs were only getting about 30 hours per week of billable hours.
In any case, good luck with your decision. By the way, while you are doing your commercial and instrument, if you haven't done it yet, get some spins in. Both the left and right and you will have that part covered. Might want to get a little right seat time if you have not done much as reacting to a student from the right seat will be a little different at first. When I took my MEI ride, the examiner had me sit in the left seat. I was amazed that he did that. The advantage was that I got to easily see all the instrumentation, which depending on what you teach in, can be more of a challenge from the right seat.
On another note, though you can build a lot of time doing this, it is no where near as much fun as the kind of flying that Glenn does and back when I flew Part 121, we had fun, which is not the case anymore.
SUPPORTING MEMBERBobWest Nyack Aviation, L.L.C. New York, New York - East Hampton, New York & Warwick, New York email@example.com