Ah, so I’m not the only one who changes all the thin cases in anime titles I hate those cheap cases where the DVD just rests on a few knobs.
I bought a 1000 of no-brand thin cases from a shop in Germany a few years ago, and just keep using those to thinpack everything and even exchange the thin cases that some titles come in. These cases have a full support ring on the outside and solid but easy to release disc holding mechanism.
I personally don’t like those locks on Amaray cases (full size) because of almost all discs I buy that get shipped to me and use them, the disc is loose and scratched by moving over the hub. I’d say try and buy a few thin cases and test them, and if you like them buy a bulk load of them, as often the design changes.
If you want double thin cases, Alternate.de has good ones, I think they still stock them.
They smell a bit because they don’t use virgin polypropylene, but recycled stuff as well. But they’re good quality and I packed a lot of those cheap French-subbed box sets in very little space with these.