Sad you threw your belt, but happy this got brought up again! This is a part that should be included in every spares kit (right along with fuel/water separator, engine oil, ATF, gear oil, filter wrench, duct tape, plugs (not necessarily iridium), impeller, etc.
There are Mitsu and Denso part numbers on the belt, so any parts house could probably get them. I still don't have a spare but hope to fix that soon.