OK, this isn't jazz, but it's such a crazy bargain, I couldn't resist shouting it from my rooftop:
Decca Sound, The Analogue Years 54 albums (and bits of several more) from the Decca label's heyday of classical recording (the mid-'50s to late-'70s), pressed in a boxed set of 50 CDs, selling for $129.
In case you're too stunned to do the math, that's $2.58 per disc!