…and I want to sell them. Most of them are in protective sleeves and the vast majority are in good-excellent shape. Most are Marvel’s* The Defenders, The New Defenders *and DC’s Legion of Superheros from the Seventies and Eighties.
How do I find out how much they’re worth and where’s the best place to sell them?
My local game and comics shops don’t buy them and there’s no comics conventions anywhere nearby my area.
I looked around under “Marvel Comics Group” “collectors” and “price lists” but I didn’t find anything useful.
Help?
I couldn’t find a website for it, but you want to check out Overstreet’s price guide. You should be able to find it in a library or bookstore. It’s the standard reference for prices.
However, the prices you see in the guide are the retail prices. So, you probably will only be able to get 40-60% of that.
If you’re a collector, you probably want to own your own copy of the Bob Overstreet guide, which is indeed the industry standard. You can pick one up from Gemstone Tne soft cover edition will set you back $22 and the hardcover $30 plus postage. Well worth it, especially when you find that rare batch from the 50s that the elderly parents found in their attic and are selling at their garage sale for $5 dollar a box (happened to me once back in the 80s - hoo hah!)
On the other hand, if you’re just getting rid of a few and have no interest in collecting, you probably will be able to find someone who will let you look up values.
Saltire is absolutely right about the difference between asking prices and offered prices. That’s where the stores make their profits.
Good luck
I have 86 of these things, but I’m not a collector.
I found a site that had a few of the newer ones (from the Eighties) at about 1.75 apiece. If I can find some sort of price on the older ones, I may just put them on EBay with a “Buy it Now” price on the whole lot because I really don’t want to look up 86 of these things.
Although, it would give my kid something to do 
Good thought. Batch sales seem to go well on e-bay, as people bargain-hunt on quantity. Do be absolutely prepared with some idea of shipping costs, though, or you might get burned. Their weight does add up surprisingly quickly.
Check your local library, too. Many carry Overstreet along with coin, stamp, and other collector’s price guides.
But keep in mind what Overstreet himself says: What something is worth is what the buyer and seller agree it is worth.