Tactical shotgun - medium range defense

I have an old 870 to which I added a 7 shot magazine tube and 18 1/2 barrel with no choke. The front sight is a bead. This will do anything I need it to. However, I have an itch for an upgraded version. What do you recommend? It seems like every manufacturer has at least one plus a dozen aftermarket outfits - which are worth their salt?

I know that I could upgrade my current gun but once you add side saddles, a new finish, new stocks, new sights, a light mount, etc. you are close to the cost of a new gun - only you still have an old gun. It may be the functional equivalent (or even superior) but it isn't nearly as cool as a new toy, is it?

I don't care b/w pump or semi-auto but it needs to be reasonably affordable ($700-800 max). This will be my medium range gun, taking the place of what most of you might use an AR for. I have a 30.06 for long range, should that ever be needed (seems pretty unlikely). Given my set up, I might need something more powerful than a handgun but probably not out beyond 100 yards. I am not terribly keen on a pistol caliber carbine but am open to suggestions.

I want something that looks like a shotgun though - no Saigas.