I have a box that I made up, has "servo tray" type of mounting so I can see each and every servo. In that box, I have most Airtronics (of various types from the basic 94102Z up to a couple of coreless/ball bearing high torque), several Futaba's of various types, and, now quite a few, JR/Spektrum servos, all digital ball bearing. Then there are quite a few of the micro servos, mostly Hitec, but some Airtronics and a couple of Futaba's thrown in the mix.

My point is that once you start, you most likely will start to accumulate servos, as well as other components.

But, to your original question, you don't need a high performance servo for your trainer. I've used my Airtronics 94102Z basic servos on several aircraft when I started out, including on my Tiger 60, which was my second plane. It did just fine, and is the equal to the Futaba S3003, and probably pretty much the same cost. I started out with Airtronics because the Airtronics RD6000 was my first radio and those servos were included (four of them) in the radio package.

CGr.