If you buy a shotgun to shoot trap you will be very unhappy with barrels less than 30" ---- and you will have a difficult time finding a gun with 28" bbls that has a stock high enough for trap targets.
Try www.trapshooters.com they are always buying, selling and trading guns on that site.
Yea I'm really looking for 30'' or 32'' barrels but for the right deal I might do 28''. I'm looking to spend up to maybe $1200 or so give or take of course depending upon the gun.
Here's mine that is for sale, having been trying hard to sale it. When I didn't sell it this fall I figured it would be spring, trapping shooting really slows down here about Sept-Oct. I was trying to sale it locally to void the shipping stuff. Anyway... take a look.