TICKETS for the sound and light extravaganza marking the opening of the new Hong Kong Stadium go on sale this morning at a bargain $50. Urban Council chairman Dr Ronald Leung Ding-bong said the majority of the 44,000 tickets available for the event starting at 8 pm on March 11, would cost $50, with some restricted view seats at $30, and about 4,000 VIP seats on the pitch area at $300. ''This is a community event; we want everyone to be able to afford to come,'' he said, adding that these would probably be the cheapest tickets ever available for a laser and light concert by French composer and showman Jean Michel Jarre. From his office in Paris, Jarre is planning a special show, using fireworks and lasers, ''that will be different to anything he has done anywhere else'', said Andrew Bull, managing director of Arena Group, which is organising the show. More than 100 tonnes of laser and sound equipment - requiring about 100 technical staff to set up and use - will be brought to Hong Kong on a cargo plane provided by Cathay Pacific. As well as a huge stage set built in the shape of Hong Kong's skyline, the heavy hardware includes four enormous blitz spotlights dating from World War II. Mr Bull said the lights would be placed in the corners of a square, each about two kilometres from the stadium, so the beams would meet above the stadium. The second evening of the two-day gala event will be taken up with a ''Super Music Century'' concert, organised by TVB, starring Sandy Lam, Leon Lai Ming and Andy Lau Tak-wah. On Sunday March 13 there will be a star-studded soccer match, details of which will be finalised this week. Dr Leung said that although the Urban Council had made what proved to be a highly controversial announcement that it would underwrite the first day event for $5 million of public money ''that is a ceiling; we do not expect to pay that full amount''. A sell-out would return about $3 million.