NTSC consoles can be used anywhere, but they can only play NTSC games. In regards to selling in the Australian market, I know I see a lot of NTSC games listed here, but I'm unsure if the sellers are catering for a demand or just hoping to score some easy sales from buyers who don't know that the games won't play on PAL.
I suspect the later, although you can have the PAL consoles modded to play the NTSC format, so perhaps their market as the NTSC games are far cheaper than PAL
I wouldn't personally think that the market for an actual NTSC console here would be that great at all, but that's just my opinion.
In regards to wholesale buying, you would be looking at a spend of around 5000-6000K for tier 4 pricing, and of course there are 3 tiers above that, so you can imagine what the spend limit is to obtain genuine wholesale prices