Kurt,
I believe you have the cart before the horse.
Your userid is 'millerappraisals' and states you are an appraiser trainee.
But you said, "I just started doing residential appraisals under a mentor (friend of mine) part time. I have not started going to school for appraising yet, but have plans to this September". (My bold)
Since you have no appraisal education, are any of the hours you are working even usable for your experience hours? My guess would be no they are not. Do you have a MO appraiser trainee registration/license yet? Before you invest a lot of time, effort and $ in this venture check with the state regulatory agency on all of the state requirements & rules.
I hope you are not advertising yourself as an appraiser yet (Miller Appraisals???) That might get you into trouble with the state.
Take this entire process slow & easy. Don't skip a step or move forward without knowing ALL of the details and requirments. Doing otherwise could cost you a bundle of time & money.
As far as annual salary, take a look at all of the jobs your mentor has taken in over the last month, multiply times the averge fee and then multiply times 12. This should give you have a good idea what your potential is in the future. Every area is truly different on income for the following reasons.....
1. Total # of License/Certified appraisers covering the same territory.
2. Total # of appraiser trainees covering the same territory.
3. # of residences in the territory in need of appraisal services.
4. # of appraisal clients/lenders that hire appraisal services in the territory.
5. # of clients/lenders the individual appraiser has on their client rolls.
Personally, I bet you could do a lot better as an engineer.