Why am I burning through starters?

depends on what part of starter is failing? what are the fail symptoms?

Currently, the car won't start. All the lights, instruments, radio, and power windows work. I can hear the fuel pump kick on, but no clicking noise. Prior to that the car was sluggish to start, to the point that I would have to hold the key for a little bit until the starter would engage and crank the engine. Basically, it would seem as of the car wasn't going to do anything and then it would crank and turn over. I tested the battery with a multimeter and it 12.36 volts.

I should have added that these same symptoms occurred when I had to replace the other starters. I had both previous starters tested and thy were bad. Also before taking the starters off I had hit them with a hammer and was then able to start the car. So, I am pretty sure the other starters had a dead spot on the starter solenoid.

those starters are know for rapid brush wear/faults. badly designed brush system. the symptoms you describe match the fault perfectly. an OEM starter may use better brush quality and last onger or you can change yourself. here's a listing.

Thanks for the help. I just replaced the starter. It has a lifetime warranty so it just cost the time to put it in.

New, updated brushes might help either solve the problem outright, or alleviate it so your starter lasts longer for you.