Saw your post on the other forum and meant to go back and see what people were saying. I have the same gun with a .675 Indian Creek, Burris FF3, and Timney Trigger.
I look at it like this if you go buy a 870 and try to deck it out like a MaxGobbler your going to have $1,000 in it. Now it is really worth that to someone, I highly doubt it. My best guess would be $700 and that may be too high.
New 870 SM - $350
Burris FF3 - $200
Indian Creek Choke - $60
Timney Trigger - $90
Knoxx Stock - $100
Full Camo Dip - ~$250