I import my own spares. It is not cheap. However, I am guessing that a spare parts importer might be cheaper since he may add your items to a bulk consignment which might result in cheaper freight cost and subsequently lower custom duty. This is because the custom duty is charged on the total landed cost (item cost + freight). However if you go through a spares importer, you may have to wait a long time for your stuff to arrive.
Another alternative is to find a friend in Dubai, have all your spares mailed to him/her and once all the stuff has been delivered, make a trip out and bring it as personal baggage.