I've been buying my single disc DVD cases from Uline for many years. They're made for Uline by Amaray. That company makes most of the cases that the studios use. They're not the cheapest at 43 cents a piece, but they are the best IMO.
The Amaray's from Tape and Media are the best I've used or seen. Haven't bought any of those in years when they discontinued black and my wife didn't want to use gray.
I have never ordered from Tape and Media Store because they gouge you on shipping charges. Lets say you want to order 200 DVD cases. The cheapest shipping is $25.
The Checkoutstore, Supermediastore, and others have free shipping for that quantity and lower case prices. Look for "Machine grade" and you will get decent quality cases. Supermediastore used to carry them but they no linger do.
Haven't bought any of those in years when they discontinued black and my wife didn't want to use gray.
I never understood why they call them dark gray. They look black to me. But you're right, they're the best I've used.
While I agree, that TandM's shipping isn't cheap, I haven't found another case that compares to the quality of the Amaray's. The clear plastic sleeve on the others are very thin and flimsy. They crimp and get dings in them. The sleeves on the Amaray's are thicker and feel more professional to me. For me, it's worth paying a little extra for them. Decent quality won't do when the packaging is part of my product.
These also come with spline clips to use a Tray Insert for a second disc.