Where can I find the driver side computer?

I need a drivers side computer for my 96 Explorer. I believe it died, because none of my keyless entry remotes and keypads work. Ween you turn the key to acessory mode several times, nothing happens. Tee ford dealership said it would cost about $500 (i know i can find it cheaper). Is there anywhere where I can get one of these computer modules cheap? Thanks!

ebay, ebay , ebay, did i mention ebay, i needed a bunch of parts for a 99 s-10 flood damage. i entered the part numbers in yahoo search and 90 percent came back for sale on ebay.

i thought about ebay, but all i found were they remotes. ill see if i can find a part number, thanks!