I don’t recall the exact pricing, but I do recall seeing organic quinoa at Coles, where I usually do my grocery shopping. The quinoa from Coles wasn’t very good when I tried it. slope

Macro organic quinoa from Woolworths is also quite good priced with 500 gr for $6.59

Honest to Goodness sells 5kgs organic white Quinoa 5kg for $54.65. Wholesale is always cheaper.
https://www.goodness.com.au/organic-white-quinoa-australian-5kg

Pretty sure I’ve seen organic quinoa at the supermarket, I shop at Coles, can’t remember a price though. I have tried Coles brand quinoa and it wasn’t very nice

Coles brand organic quinoa can range from about $7. I would try local supermarkets.
Also try Wray Organic or a Healthy Life Store.