A friends son just graduated from high school.
He has an interest in becoming a gunsmith.
I figured I would give him a chance to put together an ar, a few parts at a time.
I would like to start with a lower parts kit install, to judge his interest.
I have kit and lower.
What would be a reasonable price to pay him?

Reality - about $20.

But for good friend, good kid, saving for college or tech school - I’d bump it up for him if I could afford to.

Also depends on the lower - a fixed stock is usually less work and tools than a collapsible with castle nut to tighten and stake.

It’s not just about assembling - it’s about using the right punches and alignment tools as well - maybe buy him some tools in lieu of payment.

Reality?
Do YOU know how to assemble an AR15 lower?
Yes?
"TEACH" him! Disassemble, then have him reassemble.
Concentrate on accuracy, not speed.

To me, installing the bolt release is the hardest part. That little tiny roll pin and being able to drive it home without marring the lower.
I've developed my own guide pin, roll pin holder and lower protector.