I would only do a 4 wheel alignment. And it is most likely the front tires were toe out that caused your wear other than excessive camber. There isn't much adjustment for the camber as it is. The rear wheels have adjustable toe also, which if off, can roast your rear tires away like you just experienced with the front.
Based on my experiences with shops, They run anywhere from ~$100-180. I would spend the extra money and go to BMW. I'm not sure about the ZHP, but with my E38, they have to put weights in the car in the front, back seat, and trunk and then use a bar to pull down on the front suspension. All done to simulate the load on the car with passengers travelling at speed.
'04 330i ZHP sedan | Mystic blue | Alcantara | 6MT | 111k
'98 740il | Schwartz 2 | Sandbeige | 5AT | 238k | lowered on Bilsteins w/ B&G springs
'00 540i sport | Titanium silver | Black | 5AT | 120k
'85 Mustang GT convertible | Medium charcoal metallic | Gray | 5MT | 215k | one owner, all original