+1 for the Pardner Pump.
Mine's actually laying across my lap as I type this. I picked it up used for $98 lock, stock, and barrel(Pun may or may not be intended. Check local regulations.)
At that price, I figured, why not? I gave it the Tacticool treatment, just because I could. Door breaching choke for the 870, Sidesaddle shell holder for the 870, Saddle-type scope mount for the 870, heatshield for the 870. Cheapo Tasco red dot sight from Wallyworld.
Awhile back it held up, shot-for-shot, against my Landlord and his Remington 887, in a friendly "Mess stuff up" shootoff using some trash one of his old tenants left behind. It's accurate enough with rifled slugs out of the 18.5" barrel for hunting hogs if I feel so inclined, and it doesn't complain about the cheap bulk shells, or the 3-inch 00-Buck I keep in it for HD purposes.
Will a more expensive shotgun be better? Maybe, I don't know. I like it the way it is. It's heavy, ugly, takes a beating, and stays in the corner of my room at night, just in case.
It'll take almost every single piece of 870 you dare throw at it, except for the barrel. The receiver was a smidge wider on mine than the 870, so I had to modify the inside of the scope mount for it to fit, but it does work. Other than being wider, everything 870 lined up and worked just fine.
One thing that was remarked upon by the people I let handle my shotgun is that it's heavy for a shorter shotgun. Lots of steel to it. It soaks up the recoil really well, and the weight is comforting....
...except for the 4 or 5 times I hoofed it up and down the creekbed by my house when it was dried up. After 3 miles or so that shotgun on your shoulder gets heavy.