IMO any car is worth exactly the price settled on. All BM's suffer with base price values on a well optioned examples, I believe. The most important thing is that first impression. If the car looks WOW you are in a much stronger position to bargin than if it looks wow. Good luck with your sale. BTW that car would command $12 - $15k here. I have been offered $25k for mine but I'm not interested in selling.
Good - Fast - Cheap: Pick any two.
E23 735i; E32 735iL (X 2 - 1 Alpine White and 1 Glacier Blue); E34 535i; E38 735iL; R50 Cooper; R55 Cooper Clubman.
E21 318i; E30 318i; E32 735iL; E34 535i; E38 730iL; E53 4.4i