A packet of peppermint sugar-free gum shows the biggest price difference in a Consumer Council survey. The gum cost 64 per cent more in a grocery or frozen food store, at HK$8.20, compared with HK$5 at a similar business elsewhere. The biweekly price survey reviewed 15 products at 18 outlets in Sha Tin. Other items had differences of between 2.6 and 54.1 per cent. The council said drug and grocery stores were cheaper than supermarkets.