Stopped counting at $10k. And keep in mind most of my stuff I bought used!!
HRE C20 - used
Swift Spec-R springs new
Eisenmann Race - used. Had Borla S-type too at one point
ACM TP - new
BPM Tune + coding - new-ish (got tuning cable from forum member)
LCI taillights - new
OEM Perf CF spoiler - new
Arkym diffuser - used
Forcewerkz side skirt extenders - 3rd party, so they were used prices more or less
AA filter - new
Countless more on maintenance and replacement parts but I guess those don't really count. Got other mods that I bought, didn't like and had to sell for less than what I bought it for for quick sale.
Current: 2008 BMW M3 Sparkling Graphite/Bamboo Beige/6MT. 1999 BMW M3 Techno Violet/Dove/5MT. On the list: BMW M2 Long Beach Blue/Black/6MT