Have you thought about making a box out of double walled carboard? All you would need is a sheet of it, an exacto-knife, and some tape. There are a number of websites with helpful hints on how to construct one.
If the piece is on canvas, you can take a couple of small wood screws, and once the piece is in the box, run the screws through the cardboard and into the frame (on the backside of the canvas - of course).
If you're taking a shot of the work, instead of a print and instead of taking the actual piece with you, why don't you use a tablet or a laptop to display it? I find the backlight of the screen helps it pop a bit more, also, if they have a projector in the room, you can hook it up and throw it on the wall.
Whatever you choose, good luck!