The decks are probably legit - the collection that this guy has for sale is some pretty incredible stuff.
If you do the math, it's roughly $65-70 a pack. It's not an outrageous price, but it is on the high side, and it's probably the reason he had to mark them down. If the deck was unusual in some way or a rare design it would be different, but it's the most common Bee deck design made. If you ask JMRock, he's likely to have a much better answer, but I think it's a little high. I bought a pack of Bicycle New Fan Backs from the same era that cost me about $15-20 less.