If you are doing a full size brew, Gryphon Brewing's bag for $40 plus is excellent (free postage). I worked it out that by the time I went to Spotlight, found a sewing lady, etc I'd probably have spent more than that in petrol and grey hair. It works far better than my former 'dogs bollocks' shaped Swiss Voile that I'd had made. Also it's done around 30 brews and still looks new.