I have the chance to pick up a colt ar-15 sporter 11 made in 1985. It comes with the
original box, (green label) book,mags, cleaning
rod and brushes, and paper tube in barrel.Seller
claims it is unfired, but this is hard to tell.
I was just wondering what one should expect to pay for it

I would expect its worth whatever someone is willing to pay for it.  Given the current uncertainty of the political landscape it is currently worth about $1500 as Kevin stated.  Now here's the rub.  In two years the AWB may sunset, in which case it will be worth about $800 or it may be renewed in which case it may be worth $2000 or more.  In either case its value will change dramatically.  It is therefore a gamble that reminds me of buying Enron stock 3 years ago.  My simple advice is if you are buying for value, take your best guess.  If buying as a shooter, get a post ban rifle.

As above, buy a post ban it will soon likely be a "preban."  I really like Armalite quality, Bushmaster selection and Colt....well, the name says it all.

The 1500.00 price seems about right...I'm selling my PreBan Sporter for 1400.00. 250 rounds thru it.  

Mine has  a Harris bipod mount on the front, monopod on the rear which added 75 bucks to the selling price.