Where to buy standard lamp fittings in Hong Kong?

Please, does anyone know where one can buy fittings for desk lamps and standard lamps in Hong Kong? I am looking for switched lampholders (the brass/plastic thing that screws into the top of a desk/standard lamp and holds the light bulb) and lamp shades (that are held in place by the brass/plastic lampholder).

Available for £3-£7 in B&Q and Homebase in UK, but the lighting shops in Hong Kong (including the many lighting shops in Apliu Street in Sham Shui Po) don't sell them. Very frustrating. Nor can I find lamp shades of the right sort in department stores or IKEA.