Kmart has quite a few Bike Shaped Objects in the 80-150 range.
http://www.kmart.com.au/product/southern-star-66cm-%2826%29-…
http://www.kmart.com.au/product/southern-star-66cm-%2826%29-…
http://www.kmart.com.au/product/southern-star-66cm-%2826%29-…
http://www.kmart.com.au/product/700c-mens-citi-road-bike/122…
There are also some kids bikes under the 80 dollar range.
Probably only good for trips to the shops etc, and preferably for people who know something about bikes. Because Kmart sure doesn't (notice the front fork of the Kodiak bike.)