I have just bought a set of roof bars for my sorento they are made by Thule, the set comprises two bars with four locking brackets. I bought the set at Halfords and they cost me around £70. I seem to remember Halfords had their own brand for only a few pounds cheaper.
With the Thule brand there was a choice of steel bars (what I bought) or aluminium, which were a little more expensive. I have just returned from holiday after using them for the first time, they worked fine, very sturdy and secure.
Hope this helps.