I don't any financial interest with any sup brand, but these guys seem to have very affordable boards and I think they are up in Queensland and they support this forum:
www.thesurfboardwarehouse.com.au/sups/ You can search this forum for the different models they sell.
And if you tell us what you hope to achieve, and your experience level and your weight, we can even provide advice on the size, width and volume you should buy (if you need any advice that is

)!