REMEMBER that impulse-buy Jesus Jones CD, or those Best of . . . Christmas gifts from a well-meaning but misguided relative? Well, no longer need they sit at the back of the CD rack gathering dust. Instead, there could be money to be made. Used CDs can fetch between $10 and $60 in Hongkong. To get an idea of the going rates, we took four CDs - Robert Plant's Fate of Nations, Ice-T's Home Invasion, Ace Of Base's Happy Nation and The Orb's U.F.Orb - to two stores in Mongkok's Sino Building. At CD Music City, we were offered $40 for Plant and Ice-T because they looked ''pretty new''. Ace Of Base was given a quote of $45 because it ''looked like it had hits on it''. Finally, we received an offer of $50 for The Orb. The reason? ''I don't know why. I'm just guessing,'' co-owner John Tang said. Alas, the staff of 138 Specialist across the hall examined all four discs with a mixture of confusion and disinterest. No offers were made. ''I wouldn't buy them because they're not popular or a hit,'' said the store owner. Quick as a flash, we whipped out U2's The Joshua Tree and were offered $45. Better take all those unwanted New Kids On The Block CDs along next time.