Look for a manual wreck - buy whole and use the bits you need. Fix all the other bits your car needs from the wreck. Resell the wreck complete with all the parts you take out. Parting takes ages, leaves you with scrap and is a general PIA IMO.
Good - Fast - Cheap: Pick any two.
E23 735i; E30 318i; E32 735iL (X 2 - 1 White and 1 Light Blue); E34 535i; E38 735iL; R50 Cooper; R55 Cooper Clubman.
E21 318i; E32 735iL; E34 535i; E38 730iL; E53 4.4i