THE robustness of the market has seen prices for brokers' seats on the stock exchange triple from around $450,000 last year to $1.8 million. This figure is expected to rise even further with continuing demand. In an attempt to ease the scramble for seats, the Stock Exchange of Hongkong is considering allowing members to open branches. ''The stock exchange will not issue further membership seats, as the existing number of 929 shares is high enough. So we are considering some relaxation to allow members to open their own branches,'' said Ms Choi Chan Po Sum, first vice-chairman of the exchange. ''The price seems to have gone up a great deal, but it is not as high as the $2 million recorded back in 1973, if you add the inflation rate,'' she said. Ms Choi compared the price for a stock exchange seat with that for a taxi licence, pointing out that the latter now costs up to $2 million, in a business which was far less risky than stockbroking. Before the market crash of 1987, the price of a broker's seat was around $900,000, and it had remained steady at around $400,000 to $500,000 after the crash. However, in June last year, the price began to rise steadily after the court acquitted six former exchange officials of a corruption charge. ''The demand is mainly from foreign and Chinese firms, because many people have turned bullish on the market,'' she said. The chairman of the Hongkong Stock Brokers Association, Mr Henry Wu King-cheong said: ''The present condition is one of no supply at all. So if any seat-holder is willing to sell at $2 million, the deal can immediately be done. ''The last seat was sold for $1.6 million about two months ago by way of tender, and the price trend is still going up.''.