The cost, yes another reason to be wary of how often, and who, we take shooting...The time involved pre and post shooting also. If I take someone to the range and do handguns I make them pay for the ammo. I generally buy some S&B 9mm (about $99.50-$110/250rds) and then I keep the brass for reloading. With rifles I charge them by the round at $1.50/rd. It might sount miserly, but what choice do I have? That guy the other day shot 150 .308 hand loads plus I drove up there in the big-dog so about $60 worth of diesel...My time, the cleaning etc. I think it's fair.
I like that story of the shotgun, especially that you were shooting it better than him. So many times people blame the gun and will dispose of it for another...Only to find they shoot the same! You were the winner there for sure. my shotgun is a scrub gun, I use to sling on my back when pig hunting, a back up. It's a 12ga Fausti U/O and is about as basic as it gets. I've had it since 2002 though, and it's not failed me. Scratched, scraped and ugly as hell, but well-used. Lol. Cost me $950 at the time...Probably worth $150 now!
I'd like me a Beretta, my mate has a nice one that I keep asking him to sell me, at 50% off...Lol. Same deal as you and your mate. I'll keep plugging away. (We shoot the same though, in fact, if I'm honest, he's better at shotgun than I am.)