I think between 2.5 and 3.5 is probably more realistic and I wouldn't be surprised if it went higher. A couple of AFA 85's came up on ebay a while ago and I think one reached around 6k with the other not selling for it's asking price of around 7k. This last one went back up for sale recently at 6.5k and didn't sale.
These things do go in waves though and an 85 grade should always go for a fair bit more than an 80 most of the time.
Best of luck with the hunt though.
Ian