HONG Kong offers the best bargains for tourists seeking to buy 'luxury' goods, according to a survey by the Economist Intelligence Unit. The prices of 15 products, ranging from Rolex watches to Polo shirts, were gathered for the survey. In Hong Kong these goods cost 29 per cent less than the average of their cost in the 11 cities in the survey, the report said. And Hong Kong's bargains are getting better, the survey said. Prices for the types of goods covered were 22 per cent below their average prices in 1993 and 20 per cent below prices in 1992. The best buys were gold necklaces and Nintendo's 'Gameboy' video-game, according to the survey. Singapore and Taipei followed Hong Kong as the second and third ranked in the survey. The 1994 survey gathered prices from up-scale shops and department stores.