I'm after some advise! After a C*** Up with my E53 that I should have been collecting tomorrow I am left without a new car

I have had a couple of cars with iDrive and really like the functionality. REALLY want an X5 but have limited budget, the smart car for me is a 5 series Touring, but the X5 is calling

I currently have 20k to spend. I am only interested in going to a main dealer (yes, mad I know!) this will put in a in 2006 E53 no problem with a half decent spec. I can however put this off another 5-6 months and go to 28k which should put me in an early 2007 E70.
What would you do any why!
Thanks