Interesting comment by Synchronizor on Remington 870 Forum:

“Here’re my thoughts for a more budget-friendly take on what you seem to be looking to do (a functional HD build):

Shotgun for Home Defense Training

Shotgun for Home Defense Training

Stock furniture works fine & fits most adults who aren’t wearing armor or a chest rig ($0)
-For help with recoil, an improved recoil pad ($25 – $45)
Wilson Combat +2 mag extension; a bit heavy & unrefined, but tough & reliable ($45)
-A stock bead works well for HD ($0); or you can get a glue-on tritium bead for the dark ($65)
Velcro sidesaddle ($12 – $20 depending on capacity)
-Factory Express finish works fine for HD; just oil it occasionally ($0)
Inexpensive LED white light (~$30 + maybe $15 for a cheap clamp-on rail)

With shipping, call it roughly $100 – $200, and you have a gun that’ll do pretty much the same thing as your above setup in a HD application. Start with that, get some trigger time, maybe take a class, and then you’ll have a much better idea whether or not any of your initial list of premium add-ons are worth the money.”