Get Thule or Prorack, dont go for the cheapies from repco, You should be able to find the model number of the type of clamps and bars you need on the thule site, then try to find some on trademe. I got my cross bars and clamps off trademe and got my ski holder from hyper. Cost about $500-$550 all up i think.
Edit: You are probably lucky not having rails like my car, it was f**king hard to find the right clamps for mine off trademe, took a month or two. There seemed to be lots for cars without rails.