My next door neighbour gave me an ad sheet he got from an auction house. They have an online presence. This particular auction features some Toyota utes and a number of little Suzuki bikes (110-125-150cc 4-stroke) which look like good pit bikes.
http://www.graysonline.com.au/sale.asp?SALE_ID=7170
Not spamming, just looked like useful info.
thanks,
-Brian