I also agree that this is not the part to try and save money on. Bite the bullet & get the name brand one and make sure it's the correct one for your machine. Like ckcowl, I started with an inexpensive generic that lasted only a few months. The brand name replacement is 5 years old and still working well.
In addition to making sure that you are installing it properly (it can be tricky!) how are you quilting with it? A walking foot will SITD, or do gentle curves, not FMQ. Are you supporting the quilt properly? The foot can't pull the whole quilt thru the machine by itself, you have to make sure there's no drag.