What do you want to do? It's hard to answer without specifics.
My experience is that there are sometimes discounts for car parts as sales on generic parts at places like AutoZone and Advance. If what you need is basic mechanical stuff (brakes, starter, alternator) then you're OK there.
I don't recall ever seeing "codes" for parts similar to those you find at Bed/Bath, or the electronics big box stores. This makes me wonder whether the OP is familiar with working on cars...?