Dont buy bottles, better value from cases. If you shop round Woodstock goes for about $40 a case of 24 canz. The cans are 440mL, with 1.7 standard drinks in each. The time it lasts depend on your experience with alcohol and how smashed you want to get. I, personally drink occassionaly, eight cans will get me happy, 12 will get me off my face. So not taking into accounting how you want to drink and your experience, 10 cans a night, 3 cases, $120. Not bad if you ask me. I going down south coast for two weeks, so i be spending quite a bit on alcohol lol
Another thing, if your going with a group of mates, I reckon you should all go down to a bottlo and make a deal. Say theres about 10 blokes, 3 cases each, 30 cases, Im sure you can bargain a better deal