I bought a Mossberg 500 home defense/ field combo shotgun when I was looking. It came with a 18.5" heavy barrel and a 28" ribbed/ported sports barrel. I think it was around $300 on sale from Cabelas. I figured it was a nice set-up that gave me options. I'm glad I did, because I have used the longer barrel at the shotgun field with friends.
My intentions was to put an AR type collapsible stock on it... until I tried a coworker's shotgun with that style stock. I did not like it at all, made my wrist hurt and when firing it would slap my cheek something awful.
So, instead, I changed out the stock for a Hogue over-molded rubber stock/forend (I like the feel way better then the ones that came with the gun). I put on a mag-tube tri-rail, attached a $25 NcStar light and a cuff on the butt stock. That is about as "tactical" as I'm going with it.
Check out the combos, I think they are great values.