You can order the parts from a vendor in the UAE (Sharjah). I have found the prices to be significantly cheaper than what is charged by the dealers in Doha.
Then you can have them(smaller items) shipped to you via a Shop & Ship account( Aramex) if you have one. Else you can contact a cargo company in Doha, and they can bring it to Doha via road. They will need an original invoice list of all the items that they are transporting. Try Bestline Cargo. I have used their services and found them to be competent.