I went to my local department store, headed to the fishing and hunting area, and bought a great big multi-drawer tackle-box. It's awesome. I currently have two.
One has a top and bottom layer, each of which is about 24" by 12" about 3" deep. The layers are divided into a bunch of compartments, each of which is about 2" by 3". I can fit my largest Large minis in them no problem. The whole thing snaps up tight and has a carrying handle. It cost me about $8.
The other one is basically a nylon case with three big pockets (one on each side, one in the front). The pockets are big enough for all my dice (I have about 500 dice--really), a stapler, a roll of tape, scissors, markers, pens, pencils, all the stuff I need at a game. The inner chamber has 4 plastic boxes, each about 10" by 8" by about 1" deep. Each is made up of a bunch of little compartments, with removable side walls. I get all my medium and small minis in these. This one cost about $12.
Dave