Do a search. There are a couple of threads here with various suppliers to check out for those.
Ditto your comments on not travelling with wet salt because it compacts & can freeze up. Made that mistake with my Pro Flo 2 once, once. (Johnny Dangerously?? LOL) We loaded it in the evening because the loader was there and the truck was there & then went plowing a bunch of closed locations that didn't need salting with the storm. So that truck finished that route at 3:00 AM and it was time to run back through and throw some salt down. Nope. Temps had dropped a little and after an hour of digging & chopping, still a block of useless, frozen, compacted from driving back & forth for hours salt, & time to switch to the back up plan.