Where to find a directory of van dealers?

[grumbas]

I'm putting together an affiliate offering targeted at van dealers, the next step is obviously getting it into the market. Where would you go about sourcing this sort of data list?

There's a million and one 'directory sites' coming up on Google but each only has a handful of dealers listed. The boss is adamant he's not going to pay the likes of Experian for a list, and I really can't see the point of trawling the net for days on end to manually build a list of I suspect only a few hundred!

Any suggestions?