Just using parts from Oreilly's as an example.
List price on Thermoquiet pads is $52 for the front and $67 for the rear. Generic rear rotors are $42 a piece by 2 is $84; total parts at retail list is $203. Lets just say instead of cutting them he threw new rotors on the front @ $43 ea and you're at $289 retail cost for decent parts. I'd say a not insane markup would be ~15% over retail so for your average joe it would cost $332 in parts (prolly a little more than that).
I'm shady on the exact math but its safe to say a commercial account pays at most 75% of retail cost, so at most his friend paid $217 for parts.
Most places I've seen charge 1-1.5 hrs per axle for a brake job, regardless of turning rotors or not. Split the difference and say 1.2 per at $100/hr and you're at $240 in labor.
So your average joe would have paid $572 + tax + shop fees for brakes all around with rotors, probably more with a higher markup on parts. Him giving you parts at cost would be $457, so he probably knocked off a half hour of labor at the same time. Pretty reasonable assumption he could have used decent parts and just gave you a friends/family type hookup. Either way your go about it, sounds like a decent price for what you had done.