I buy most of my mods used. So many people sell barely used parts because they want to try something different or upgrade to a new car. I also sell my cars stock and part-out the mods separately. It's still expensive but the cost is minimized with this approach. I have been lucky enough to sell some parts for the same price I paid for them.
'13 SSII M3 Coupe - KW Clubsport 3-way, Akrapovic Evolution, ESS Tune, StopTech Trophy, IND Euro Front Bumper and Gloss Black Mirror Covers, TMS Studs/Lugs, BMW Performance Carbon Fiber Spoiler/Interior Trim/Center Console, BMW Edition Grills/Gills, BMWPedals Extended DCT Paddles, Advan TC3 18x9.5 & 18x10.5 - Hankook RS3 (Track), HRE R40 - 18x10 & 18x11 - Michelin PSS (Street)