how about the time associated in removing all said parts, then the time it takes to sell all individual parts. The e21 specific crap wont sell. then the time and cost to get rid of the shell.
You aren't splitting the car because you don't want to deal with any of that shit and I don't blame you but the asking price should take into account more than just what the parts are worth separately.
and the "make your best offer" line is just asking for people to low ball you. You know what you want for it. Give a number a bit above that and let people talk you down to your number, win win. They feel like they got a deal and you got the price you wanted to begin with.
You seem to always have problems selling stuff... maybe you're the common denominator...