At the moment I'm paying £70 for a half in London so £20 for an eighth is alright. If there's five of you putting in then you mayaswell put in few quid extra each and get an oz for around £120.

As for keeping it in a bag for a month or so, think about getting a small tupperware container or go to the camden or brixton markets and invest in a stash box. It'll keep your weed fresher and keep the smell in.