Thanks for the info, Brian!

I'd be interested in seeing what kind of flight times he's getting from this combo.

I have a similar .40 trainer conversion:
Mine started out with a Tower Trainer .40 for the airframe. To that I added a Kyosho Endoplasma ($20), a Great Planes GD600 gearbox ($13), MEC 10 tooth pinion ($5), Great Planes C-50 ESC ($50), 10-cell stick pack (~$45), and APC 12x8 Thin-E prop ($5). Charger is a Hitec CG340 ($40). Motor mount is a carefully-crafted plywood "yoke" that was epoxied to the cowl cheeks (free, used scrap wood from the shop).

Total power system cost: $178, plus shipping. I wouldn't consider it adequate for a beginner, though, because the flight times are too short. Mine gets only about 8 minutes, if I fly at minimum throttle, go until the motor cuts out, and make an emergency landing. In my experience, a newbie's knees don't stop knocking until about 5 minutes into the flight. With this setup, we have to land just about the time he/she gets calmed down

Throw a couple-hundred dollars worth of LiPolys at it, and you have a lighter plane that the student can actually fly long enough to learn something. Unfortunately, that pushes the total cost up over $400, just for the power system. Then you have a cheap brushed motor being pushed to its limits for extended periods of time. It won't hold up very long, maybe . Replace the Endoplasma 3 times, and you could've bought an AXi 2820/10 that would last virtually forever.