Perhaps you could have a look around this site
<<Reserve price
The property officially becomes ´on the market´ when bidding reaches or exceeds the reserve price.
If bidding does not reach the reserve price, then the highest bidder usually has the right to negotiate to buy after the auction.
If the vendor does not set a reserve, the property is on the market from the first bid.
You should also advise vendors that you cannot accept a bid from them if they have not set a reserve, or the reserve is exceeded.>>
http://www.fairtrading.qld.gov.au/auction-reserve-prices.htm
<<Reserve price
The property officially becomes ´on the market´ when bidding reaches or exceeds the reserve price.
If bidding does not reach the reserve price, then the highest bidder usually has the right to negotiate to buy after the auction.
If the vendor does not set a reserve, the property is on the market from the first bid.
You should also advise vendors that you cannot accept a bid from them if they have not set a reserve, or the reserve is exceeded.>>
http://www.fairtrading.qld.gov.au/auction-reserve-prices.htm