You can pick up the tool at most auto parts stores for about $5, if you have damaged or missing door eschtcheons behind your interior handles you can also pop the spring steel retention clip off the handle with a common small screwdriver. We have pairs of exterior handles on sale here
http://www.gmcpauls.com/SALE_SPECIALS.htm
or you can get them singly on this page
http://www.gmcpauls.com/door_parts2.htm
Your main concern when buying new or used exterior door handles is the metal tangs that hold the door handle button return spring in place, these tangs are often cracked from from use and age on used ones and there are a couple of manufacturers of the new exterior door handles that when they are bending these tangs to hold the plate in place that is cracking the tang which causes them to break very quickly. Our new exterior door handle retainer plate tangs are inspected and mechanism lubed before shipping to be sure that these are not damaged to ensure long life and trouble free use.
GMCPaul