Most commercial dealers will have them - the same places you'd go to buy a van (in the UK at least). I've used them for work in a couple of contexts (usually Mazda ones for whatever reason) and they've been great.
Even then, I'm not sure they're that common. Most contractors/plumbers/movers/etc will have a Transit or something similar. There are a few, farms sometimes have them, but I would find it strange to see one parked outside someones house.
