Those speakers mentioned are active speakers so you dont really need anything else, plus they already have volume control. I got mine 2nd hand, don't know the retail price but I reckon its between 200~300 range.
Esden Trading and Hung brothers...both at simlim sq...3rd level i think.. carry behringer products. They also have official dealer here..pro music i think? you can check their address and contacts from behringer website. Hope that helps.
