I've had the 1.5 ton aluminum racing jack from Harbor Freight for about 6 months now nad it does really well lifitng out BMWs. They can be had for around $60 if you time the coupons right:
http://www.harborfreight.com/1-12-To...ODY1NiJ9%0D%0A
I also have their larger 3 ton steel jack and it's a monster. I use that on our bigger vehicles but it's way overkill for X3.
Like Bee mentioned above, be sure to get the jack adapter pad otherwise you'll squash your plastice lift points. I've used a cut off 2x4 in a pinch but the adapter is well worth it.