Skybus is cheapest. Buy a return. Walk from the bus terminal 500m to the Casino- south bank. Many bars & resturants on South bank.
The other transport option is a taxi, but will cost more.
http://www.melbourne.com.au/southban.htm
http://www.thatsmelbourne.com.au/Pla...outhbank.aspxe
http://www.southgatemelbourne.com.au/