Local transportation is cheap. Download the app Easyvan and there you can select from and to places and get a price.
Different options are:
Van - I've transported bookshelves, TVs, bicycles, wardrobes and nearly everything.
Van Move it Yourself could be $80-250. Usually slightly cheaper than a taxi.
Van $80-250 + help (need negotiate $400/half day, $800/full day per person)
5 ton Truck. I just use the 5 ton because it fits everything easily and I know the driver, reliable, even picks me up for free and takes me there and back. Fee is usually $550 or $1000 with one man helper included.
Again based on distance so these rates are pretty far distances. I've found furnitures all over HK, and collected them. Usually need to travel for the good stuff.
Discovery Bay will cost more. Islands I have no idea.