just an FYI, have you checked the drop front boxes at this location;
I got several for a project I was working on. They are the same as the Light Impression drop front box, except the color which is gray. A lot cheaper. Less than $ 10 for a box that will hold 22 X 28" prints. They are not the black portfolio box, which may be what you are talking about. I got 3 for a bit more than one would cost at Light Impressions.
This may not fit your needs but just wanted to pass along the information .