Hmmm, that's a toughie. What your instructor is expecting is basically a .40-size trainer with an electric motor. What you're expecting is to not pay any more for it than a .40-size glow trainer. Problem is, there ain't no such animal...

You can get an RTF .40 glow trainer for $270 right now, and have all the fancy gear you need for another $100 (electric starter, field box, battery, glow ignitor).

The closest match I can think of off the top of my head is the Hobbico Superstar EP. It's 3-channel (rudder elevator throttle), but a good rudder plane flies as well as any .40-size trainer with ailerons.

Are you opposed to doing a conversion? There are a couple of threads in "Glow to Electric Conversions" asking about converting .25-size trainers. The Endoplasma power system I recommend over there will work in any .25-size trainer like the Sig LT-25, Sig Kadet Seniorita, Great Planes PT-20, Goldberg Freedom 20.