I get mine from Half-Priced Books, The Exchange, or Disc Replay. Look for used bookstores, many times they will have a used dvd section. Obviously, used dvd stores like Disc Replay or Disc Go Round. Flea markets and pawn shops are great places too. If you don't mind paying the price, Barnes & Nobles can be a great place to find classic and cult classic horror films, they will order movies for you too if they don't carry the title you're looking for. Same goes for online buying, if you don't mind the price or don't have a choice, you can pretty much find anything you are looking for. I prefer the shops as opposed to online but I think its just because I enjoy the hunt and find aspect of that kind of buying, it can be really gratifying when you find those hard to find classics, plus it can be a lot cheaper.

I check the Salvation Army whenever I'm there. Depending what color tag is on sale I've found some interesting vhs videos anywhere from twenty-five to fifty cents, like Ed Wood's GLEN OR GLENDA and the French THE GIRL ON A BRIDGE. All depends who donates what.

For online, Amazon.com seems to be a cut above any other online source. Half Priced Books is a good choice for physical location if you have one in your city. Other than that, if you have a comic book shop in your town, they usually good about carrying gently used movies (at least the comic book stores in this area).

I collect the SHIT out of DVDs so let me give a few suggestions

depending on where you live

Big Lots is surprisingly awesome for finding stuff to complete a series for pretty cheap, stuff like Friday the 13th... franchises, things of that sort. I don't think I've ever paid over $5 for anything they've had. They usually have a pretty good selection this time of year. Some stuff I was surprised they had, "Thirst" and "Otis" never thought to find those there $3 each... Sadly I already owned them

Walmart.com... Seriously they have pretty sweet deals.

If you don't mind paying to import things normally OOP in the states go to www.dtm.at think they are based out of Austria so you'll pay like $20 in shipping but I found stuff I've been looking for for YEARS there. You'll need a region free dvd player though.

Also try Diabolikdvd.com, sometimes over priced on things but it's very likely they'll have what you're looking for

Also, Pawn shops. I've found some great stuff in pawn shops and generally stop at any new ones I pass.

hope this helps.

oops forgot to mention SecondSpin.com crazy low prices. I was somewhat nervous to place an order because of how cheap everything was priced, but I have an order on the way. Will let you know how that turns out.