Yeah, this is a fairly frequent problem. What gets me is when I order things from Europe and their bubble mailers are wimpier than the typical ones you find in the U.S., or so it seems. I wouldn't normally shed a tear of a cracked case except one album I picked up there was a unique title sticker on the case and the cover had cracked right through the sticker all because it was just the disc inside a really thin mailer. My bigger complaint is that nearly every double-CD set with the flip-tray arrive broken and the all-clear 2-sided flip trays are not easy to find (I suppose if you buy in bulk, but can't find them locally, only solid black flip trays)... however, I figured out a way around this... thrift stores! There's almost always a really bad religious 2-CD set that's in near perfect condition with those clear 2-disc trays and I buy them for a couple bucks when I need one.
For my Numinamusic orders that I ship out, I buy these cardboard boxes specifically designed for CD sales. I have ones that hold 2 CDs at a time and use them for 1 or 2 order sizes. If it goes up to 3 I'll use a bubble mailer with some cardboard inserted on the two ends and for more I recycle boxes I have and/or cut out my own cardboard mailer - which is kind of a pain in the ass and can take 20 minutes to size it up and cut it just right and tape it all up, but it beats wasting more cardboard by buying a lot of oversized boxes and stuff. If I was high-volume I would do that, but it's just not economical for me at this time.
Hypnos, Roach, Rich, and Projekt have always had perfect packaging from my experience.