This will be my first shotgun. I am looking at a shotgun for trying out sporting clays, possibly hunting, possibly 3-gun competition, and home defense. Since this might mean switching out barrels for different purposes I am looking at either a used 870 (no express) or a new 500.

I went to a couple of stores yesterday (Cabelas and some local places) to look at used shotguns. Since I can get a new Mossberg 500 for $209 with a 28" ported barrel, I was thinking $150 for a used one. For a used 870 I was thinking $200-$250. Unfortunately, nobody else seems to think this. The stores did not agree with me. THe cheapest I could find was a used 500 for $199.

We have a large gun show coming up Thanksgiving weekend. Do you think I should  just go for the new 500, or try to find a used 870 at the show?

Unfortunately, the pawn shops in my area stink. The majority don't even deal in firearms.

As always, try several of each model and buy the one that fits you best. If you find yourself developing a preference for either the 870's or the 500's safety, then buy that one. 

There you have it.  "Fit" means everything in shotties.  If the 870 had the same safety as the 500... ooh baby.