cycle carrier...

i'm looking into changing my rear bike carrier for a roof set up as im too wary of my bikes hanging off the back of the car. Just cant settle with them there (and its marking the paintwork)!

Anyway, i have done a search and a few threads have shown up on the subject but can anyone share their experiences of the roof mounted carriers. I assume i need to purchase roof bars and the cycle carriers themselves?

is it best to get both these from skoda or maybe just the bars then get the carriers elsewhere?

I just want to make sure i get the right kit this time any idea of how much im looking at to be kitted up fo say 2 bikes ?

cheers!