Nice find! Of course, there will be the "It's only shooting ammo, so sell it off cheap" gang. I put a few boxes of old ammo on my table last weekend at Regina. It was not in unopened condition by any means. Poof! It was gone. I averaged around $35 per box. If you are going to sell it at gun shows, make sure you put the boxes in baggies and put a large sign nearby that says something like, "PLEASE ASK TO HAVE BOXES OPENED", otherwise people who have no clue about opening pristine ammo boxes will have them wrecked. Even the dealers who have their ammo sealed with cling wrap will pry other dealers boxes open without asking.
One guy asked if I had owned a store. When I told I hadn't, he asked, rather belligerently how come I had all this ammo (all 10 boxes!). I told him for the same reason I had all the other stuff - because I bought it.