http://dubaiaudio.com/ Run by two brothers who are knowledgeable in their field, they will give you unbiased honest opinions and will give you the time and space to enable you to thoroughly evaluate the options available to you, more importantly; they will support you with an after sales service above and beyond the call of duty, a rare thing in Dubai! but as with any other retail business, the prices advertised are for negotiation and the deal you end up with is entirely dependant upon your negotiating skills, good luck!
BTW, these would be AV (Audio/Video) installations.