[XFILES]

Since I know relatively little about shotgun prices, I thought I would ask here. I recently saw a Mossberg 500A in my local pawn shop. The gun seems to be in about 90%-95% condition, has a 28" (?) ribbed barrel, wood furniture, and is missing the choke tube. Owner says I can get it for $100 OTD (he has $200 on the price tag). Would this be a fair price? Also, since I no longer hunt and only want it for homeland security, where can I get an 18 or 20" barrel? Is it possible to cut the existing barrel down? Thanks.