NO! Buy the newest, lowest mileage X with the most remaining factory warranty that you can afford if you are going to do this.

I have owned my 2001 4.4i X sport pkg 3 years, have only put 15k miles on it (104k total now) and have spent over $10k just keeping it on the road.
My problems were:
1. Window 2 motors
2. Water pump
3. T stat
4. Front cv joints and boot
5. Had to replace front tires because of # 4
6. Battery
7. Alternator
8. Battery again 1 year later
9. Alternator again (have a short somewhere in the $1200 DSP amp which I replaced the amp and still have the short)
10. DSP Amp
11. Oil tubes froze up and blew out, almost lost the motor. BMW came out with an electric heater to heat those tubes so it won't happen anymore, but it was cost prohibitive for me to buy that part when I had the $3200 repair- gaskets had to be replaced too
12. Brake job with sensors and 4 rotors
They are good looking cars, my 4.4i was way more powerful than my 2006 Range Sport,
BUt it isn't worth the trouble!

I'm selling mine $9,999 CO craigslist. Runs like a dream with the latest $4k I dropped into it- but it needs an aftermarket radio as I unplugged the stock radio due to the short draining the battery and stressing the alternator...