$810 installed is not far off especially from the dealer. You should've asked to get a through checked on the wheels though. But since they didn't say anything and mounted on the wheels you should be good.
1. E90 325i/328i/330i Eisenmann Race Exhaust 2 x 76mm (Used for 30000 miles) $680 OBO
2. BMW M3 Steering wheel $430 OBO
3. BMW Original E90 Blacklines $230 OBO
4. BMS Powerbox $230 OBO