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.
2008 E92 M3: Sparkling Graphite | Bamboo Beige | 6MT | CF Roof | HRE | Catless Eisenmann Race | BPM Sport | Swift | Arkym | Mode Carbon | M.Perf