Usually go up to Albury for a squizz, but its only an hour up the track got us. Its not huge, usually spend a couple of hours there. From memory, last time we went there would have been 6 or so CT manufacturers there, as well as a similar number of Van suppliers. A few 4WD suppliers also in attendence.
Then perhaps 30 plus trade stall holders, but not a huge number of outdoor goods suppliers like at Flemington.
Would I drive 3 plus hours from Melb, or more from Sydney? Perhaps not worth the effort IMO, but hey, if you combine it with a weekends sightseeing @ Beechworth/Bright or winery visiting @ Rutherglen, anythings possible.