I use a castleford 4 pipe case that I got for like $20-$25 a few years ago.
There are a few things I don't like about it. But I havn't been sold on anything else just yet. Overall it's very nice to have. But it kind of feels like I'm carrying around a purse.
Often I'll make my wife carry it in her purse. Incognito
If traveling out of the US etc. I have a couple of large Oakley vault cases that work very well in my carry on. For around town a large semi-rigid sunglass case; holds everything I need.