So I'm making room in the garage so I'll have a place to work, do engine swaps, whatever, without looking like a complete boob out in the driveway. In 2008, I bought all new brake hardware and a hydroboost kit, and today I found the two caliper cores that I never returned. The receipt at the time listed the core values at $11 each, so I should be getting $22 or so back, right? Nope! AutoZone gave me $43.50. I don't think this was a mistake, as the store manager did it for me and gave me a lot of crud for "bringing in cores from 2008". I'm assuming the price of the parts and their respective cores has risen over the years, and their system gives you the current value of the core rather than the one listed at the time of purchase?
So, bottom line: if you want to maximize your returns, wait a few years before cashing in your cores!