Dammit. This thread just made me realize that I've already blown away more than $15K on mods for my MZ4.
I think I need to have my GF start managing my money for me now.
Hardtop: $2K
BBS RGR's + Goodyear Eagle F1 tires: $4,500
2nd set of rims + Goodyear Eagle F1 tires: $2600
Eisenmann Sport: $2K
TCK coilovers + install: $2900
Strut bar: $330
M-tech side skirts: $500
Window-tint: $200 (twice)
ZHP gear knob: $60
Painted reflectors: $50
Smoked tail-lights + install: $100
Blacked-out grills $50