Perhaps the clerk who priced the box set didn't inspect the Mosaic box set carefully. Probably assumed there were 5 double CD jewel cases. A total of 10 discs, therefore 10@$8 = $80.
Ebay? $300 - $400
Hmm... my set contains 6 jewel cases: 4 with 4 discs each, and 2 singles (in their own thinner box that also contains the booklet).
At any rate, a great deal. Not as good as mine, though. I bought a used set (mint) from a local store in 1994... $40. Highway robbery. To this day I have no idea what they were thinking (6 X 7 = 42... round down?). I bought a few other sets from them around the same time, also good deals, but nowhere near as good as that.
Well, maybe they thought the 4 quad jewel cases were doubles, so 4x2 +1 +1 = 10?
$40 - Another theory: They inspected the first box that had 2 single jewel cases and assumed the 2nd box also had 2 single jewel cases. Total 4 CDs @ $10 = $40.
Nat King Cole for $40? Maybe they thought MOSAIC was an offbeat cheap re-issue label. (it's black and white, with no color photos or printing)