Yeah, I've been thinking about this too as I'm starting to stock up on take-off parts: Seats, Steering Wheel, windshield, fenders, dual headlight brackets, stereo, bolts, etc.
I did get rid of the stock windshield, but after shipping, I don't think I got $5 out of it. I'm trying to get rid of the fenders now for someone who is doing a project here (they're boxed up already right next to my desk), but even the shipping on those is $50 and I'm giving the fenders away for free!
It comes down to is it worth it to remove the big mods when you sell the SS and then try to sell those aftermarket? I mean, how much could I get for a set of used Cipher Seats that are already cracking around the edges (just 6 months old)? Would it be worth $200 to someone to try to buy from me for $100 and then pay $100 more in shipping charge when you can get a brand new set delivered for $300-ish?
I think I'm going to trash all the big stuff and just keep the small stuff around (bolts, stereo, etc.) to help out members when needed.