For a while, I was running games for the local RPGA, which meant going mobile with my gaming materials. I found a rolling tool box at Wal-Mart that worked well for a while. It was about $20, though I don't know if that is a normal price. The tool box is basically two open boxes that stack on top of one another and then attach with clamping handles. There is a tray for small tools that sits in the top box. (I use that for pens, initiative cards, and props.) There's a little pull-out drawer sized for screws and such, which I never use, but could hold dice. On the very top there are two small container-sized boxes with snapping lids that are perfectly sized for a couple of decks of cards or a dice bag. There is a handle for lifting and an long pull out handle for pulling it along behind you as it rolls.
Now, I will say that there are two problems with this box. The first is that the handle is too short to roll comfortably. (I'm 6'2".) The other is that over the past couple of years, the sides of the bottom case have warped a bit, so it's a pain to get it to snap back together after I'm done. However, I have seen some more sturdy models at Home Depot and Wal-Mart that were a little more. The ones at Office Depot tend to be overpriced, in my opinion.
(I never claimed to be funny. Well, not at ENWorld, at least)
