Why are prop, non functioning guns way more expensive than airsoft guns?

I'm doing an NCR Trooper cosplay and what I've noticed is that buying an M16A1 airsoft gun and some brown paint for the furniture is WAYYYYY cheaper than buying a non-functioning prop. Like, the website I saw listed an M1 Carbine Airsoft gun as 250 dollars but the prop version is over 1000. What gives?