Judy, if you're going through so many irons I have to wonder if you have "dirty" power like we do here. It fluctuates constantly, so many things burn out quicker than they should. Do you have them plugged into a surge protector? If not, try that. And if it doesn't help, I would say buy the cheapest iron that does the job. If they won't last, no sense spending a lot of $ on them.
Good luck.