Where to get a 84BB? and other questions

I keep seeing posts of people getting 84BBs from PSA for less than $300 but looks like they're out of stock; where can I still find one for that price? I swear I always seem to miss the boat...

My local Cabela's has a whole bunch of 85BBs for sale for $360. Is that a fair price?

Finally, besides the magazine size, what other differences are there between the 84BB and 85BB?