He is asking about developer unlocked, not SIM unlocked.if you buy from THECARPHONEWAREHOUSE ( As bad as they are with things like customer service and dealing with a assistant with the IQ of 10 ) get passed all that and the lumia 800 you get is already unlocked.
I believe you can get a student dev unlock with the possibility of installing 3 homebrew apps.
Check Chevron and see if they've got unlocks available, if not then there nothing to do atm.