I'd actually grab a bunch of them from the junkyard if they fail that often.
But before you do, take off the door trim and look at your lock assembly. Does it look corroded? If the actuators fail often, it is usually because it needs to work that much harder from gummed up mechanisms. Any time I have the door trim off, I spray the assembly with a penetrating lubricant like Honey Goo. If you roll down dirty windows a lot, I would switch to a dry lubricant like graphite or Teflon to keep dirt from collecting.