for a weber setup, youll have to import. i happen to come upon my skracing carbs by luck. theyre a hybrid between the mikuni and weber designs, with slightly less tapered throats, so i thought they would be more expensive, but i found them on ebay for $350AU. check out gempartsaustralia or gemparts on ebay, he's a queenslander who has a wide supply of carburetor products and know-how as well.

but webers are expensive, and you have to look around a fair bit for quad carbs. a pair of dual sidedraught webers could set you back anywhere up to $1500 if theyre a matched pair. but if you look around like what i did a month ago, you can stumble upon a set of quad yamaha r1 carburetors with linkages and manifold for $150US. snipe around on ebay, you'd be suprised what you can find.