Parts: The Arnott remanufactured air struts were $460 each, and I will receive a $50 core fee refund for each, which works out to $410 per strut.

Time: He is a pro and made the work look very easy. It took him about 2.5 hours (1.25 hr each) to change both air struts by himself. I offered an extra set of hands when needed, and he never asked me for help.

It has been about 8 hours and hasn't lost air, so I am hoping this was the fix.

Just had mine done. NEW front Arnott struts @$700 each (included faster shipping) plus 6.5 hours labor book rate at my indy(@$80/hr) so it was $1920 plus tax.

They were able to do it in about four hours because they are fast but they charged me the book rate because they did the sensor diagnosis and re-positioning (sensor was installed wrong which BMW could not figure out as well as the indy for the PO) for no charge and they messed with other things I wanted evaluated. SO FAR IT IS FIXED and working perfectly.

Update: After 2 days and temps under 37 deg F, the front passenger side is not losing air. Changing the air struts fixed my front passenger side sagging. Thanks for all of your help.