Any idea on how many rounds have gone through it?
When I bought mine new in 2011, I dropped about $900(ish). I wouldn't sell it for anything. Why does he want to get rid of it?
Magazines aren't bad, HK prices being what they are, Brownells has them listed between $45 (10rd) to $75 (12 rd). Add the cost of two magazines (lets say $150 if you bought them off of Brownells) and you're hitting prices on Gunbroker for a used HK USP .45.
Edit: Why doesn't he have the other magazines? I do know that people have had that extended magazine plate break, hasn't happened to me.