Just for reference, the "accountant's audit case" is what's used by many pilots - but they call it a "map case." (Or "chart case" if they fly a big 'un and went to the high priced school.) They're quite readily available new, from or through any "flyboy" center, but they don't show up in the flea markets because nobody ever throws one away.

They're sometimes available at "normal" luggage shops, and I actually got mine from Sears & Sawbucks about 15 - 20 years ago.

The real advantage they have is that they're hard-sided and rectangular, so you know exactly how much space they'll take up, and they don't tip over when you dig around in them. They're stable enough in most circumstances to provide a nice place to put your coffee mug and a sandwich while you're busy flying - or so they tell me.

Although of course it doesn't affect me, it has been noted that the usual "fifth" of your favorite lubicicant will stand upright and won't tip over in most of them. I'm not sure why pilots all seem to know that...

John