Spark plugs are every 37K. I did mine at the scheduled 37 and then again at 60. At 60 I had to pay for that and an oil change and it came out to just under $500.
'09 E90 M3 | VF620 SC tuned and coded by BPM | KW V3 | ARC Wheels w/AD08 | OnEighty Lights | AA Signature Exhaust | BMW Performance and IND trim | Recaro Profi and child seats
'13 35i M-Sport X3 | JB4 Stage 1 | BMS Intake | H&R Springs | Gloss black grill | CF Wrap and Coded by me