Here’s what you need: http://www.adorama.com/FSBP811.html
These also look interesting: http://www.clearfile.com/8.5x11_filmbox2.aspx
I’ve trying (half-heartedly) to find a similar thing as you, and have asked around at the local print shops. But they seem to deal mostly with paper-bound reams, same as the hoi polloi. I’ve gotten the impression that quality cardboard folio boxes–what high-quality bond paper comes in–are kinda rare beasties…and glommed onto quickly.
Here is the answer to the dilemma: Storage Boxes and Containers | BLICK Art Materials
Overkill, perhaps. But certainly nice, and about as cheap has you’ll find.
I use them for the paperwork for my freelance projects. Have to go to a meeting, I grab the client’s box. Also instead of a file folder to store papers for income tax.
You might need 2 to fit a ream of paper since they are 1 3/16"H but they are plastic and close entirely, keeping dust, dirt, whatever out.
$6.99 from Amazon.
Brings back memories of when I used to get all my paper from a box, it’s how we bought it, not in a paper wrap. It happened without my noticing it.
That and buying printer feed paper, connected to the next sheet, and often with the tearoff holes. Why on earth did they get rid of that? Makes great banners that way!