Someone in Australia asked this recently. There are many sources on the internet at rock bottom prices. Remember the price includes a screened box, dielectric resonator oscillator, PCB, 2 PCB antennas and a RX mixer! Think modern Gunnplexers. Incredible value!
Some are as low as $2.32 each with free shipping!!
See https://m.nl.aliexpress.com/search.htm?listType=keyword&keywords=hb100#/. This link is Dutch, but I am sure they have an English site too.