A while back, Midway or Natchez had 392's for something like $80 (just that one flavor). Thought about it but passed as I didn't need a second and it seemed a bit odd. Noticed later that they were priced the same as the 397's and C9's. If an add is wrong, the seller doesn't have to honor it. It is just an "invitation to trade".
Now, years ago, a local Chevy dealer advertised a new Corvette for something like 7,000 bananas. Guy shows up with a truck filled with, you guessed it, 7,000 yellow bananas. The dealer went ahead and honored the ad. Guess he figured, with all of the coverage by every news station in the Washington metropolitan area, he couldn't buy advertising as cheaply!