My experience - local tyre dealer with 'laser' computer alignment kit £50 ($75), BMW dealer with KDS £90 ($135). BMW wins hands down. They punch in the chassis number and the equipment loads in the settings based on factory data. If you have stock suspension this is exactly what you want. Local tyre dealer uses 'generic' settings - in my case probably 4 door instead of 2 door with M-Tech suspension. Anyway, first time round I had the local tyre dealer do the job, I noticed little difference, and after 6 months I'd had enough. No excessive tyre wear, but the car felt crap at speed. I was close to selling the thing, but gave BMW a go. £90 later the car felt transformed.