I have the possibility of acquiring a 2007 XKR. I'm curious if anyone could give me a list or some tips as to what I should look at or look out for before making a decision to purchase

 

Get it on a lift and check for leaks, and check all the bushings.

 

Besides the bushings and leaks, if it's not verified that EVERY fluid has been changed, you would NEED to do so. Coolant, Oil, Power Steering, Brake Fluid, Transmission, Differential.
Also, listen for the supercharger snout to sound clattery. The isolator inside there goes bad sometimes.
Make sure the passenger side front floor is not wet, moldy or stinky. That could mean the duckbill drain for A/C condensate is plugged.
Ensure both front seats move in ALL directions, and that the seatbacks go forward when the seat goes way back and they don't touch the rear seat side panels.
As a bargaining tool, check the date of the NAV disk in the boot. It ejects if unlocked and goes right back in. It's probably the original and should be updated (if you ever want to use the NAV).
Glove box lid should drop slowly when released. If it falls, that's another bargaining point. It's an easy fix.