Burns, Theres no great secret to buying ex-rental, just get yourself to a few garages dealing in the kind of car you are interested, and haunt them basically. The reason I say this is , first come first served.
Make sure they know what type of car you want, and have your finances in place.
Also get the garage to give it a good service check by their mechanics before you buy.
The cars are generally six months old, some milage on the clock, and not without a few blemishes.
The best time of the year is Sept. to early Nov.