I would not take a chance with a used unit since you do not know if it is locked. Plus no warranty....
If you want custom tunes, which eventually you will, I'd suggest PHP.....I am getting my unit with canned tunes from them soon for 399.00. This unit will be compatible for future customer tunes if you choose to go that route later. I believe each custom tune will run you 30 bucks a piece...
http://dygytalworld.ehost-services139.com/php/