It sounds as if you are looking for a deal on a 12 gauge shotgun. If you want new, it sounds as if your dealer has fair prices. He is below Impact once you count shipping and the transfer fees. Forget the pistol grip. Get a real stock. Shoot a friend's with a pistol grip and thank me later.
If you want a real deal though, consider used. Go to a pawn shop. Look at the Mossberg 500, Remington 870s, Winchester 1200 and 1300s. All of these can be found in the $120 range, often less if the wood is ugly. Choose a gun with a slick barrel (no rib), that is smooth but not loose in it's action. Pay your money and take it home.
Close the chamber, drop a dowel down the barrel, and measure it. Say it's 24 inches? Ok now measure 5.5 inches from the muzzle on the outside of the barrel to get a 18.5 inch barrel (NOT 14"!). No matter what the length you measure, your computation
must end up with a 18.5 inch barrel. The extra 0.5 inch is a safety margin for error. Use a pipecutter to cut the barrel to this length. Once cut, use some 240 grit emery cloth to round the edges. If you are skiddish about this have a gunsmith chop it for you. You really don't need a sight if you are talking quick targets at 20 feet or less. I just align the end of the barrel with the grooves in the reciever top and do just fine at these distances. If you feel the need, the gunsmith can remove the old bead from the chopped section and reinstall it for you. Chances are he won't charge much.
If you have a forend that overlaps the reciever, either replace it with a cob type, or just saw it off to where it no longer overlaps. Yes, it will look like hell, but who cares? It's a defensive weapon, not your girlfriend. Install a sidesaddle for additional ammo.
Now, clean 7 lube the gun, buy some low recoil 00 Buck, and take the gun to the range, load it up and check it out. Take a course on combat shotgunning. You must learn technique. A shotgun without technique is a poor weapon. A shotgun with technique is devastating.
Here are my cheapo shotguns.
Winchester 1200 $65 at the pawn shop. Ugly as sin, but in great shape.
Same Winchester with $30 of plastic added. It was just to good a gun to leave ugly.
Mossberg 500 $25 as a box of parts, but complete. The heatshield was a gift from a friend.
The Remington 870 vs the Mossberg 500
Another Remmy vs Mossy page
Also, don't discount JC Higgins, New Haven, or Western Field. These are simply Mossbergs with lower grade wood that were relabled and sold through Sears, Montgomery Wards, and Otasco among other retailers. They have the same action as regular Mossbergs, and often cost a lot less.