How about Amazon.com? The website says that they ship all over the world, and I’ve bought stuff from Amazon.co.uk that’s not available in the US (Region 2 DVD’s, mostly).
Progress past where? I use Amazon.com all the time to buy books and DVDs that I can’t get over here, and hubby uses Amazon.co.uk for the same thing. The shipping is slightly exorbitant, but I’ve never had any problems either with the ordering or the delivery.
Also, have you tried ebay? A seller in the US might ship internationally.
One thing to double check is that US FM frequencies stepping increments are the same as AU increments.
RE shopping try the US eBay site. I’m pretty sure one of the sellers would wiling to ship to AU if you’ve got good feedback or can paypal cash to them + shipping cost.
USPS airmail parcel post is $ 25.80 to AU for a 2 lb package.
there are 3rd party shipping companies that do this. I used to use Shop the states but they seem to have gone out of business. They recommend 2 other vendors and you can get a discout going via that site.
Have you tried Ramsey Electronics? They have a lot of transmitters and radios, from basic $20 kits, to portable FM “radio station in a box” units, suitable to cover a small city.