I got the Atera aluminium bars for our Leon ST, again from Roofbox and very happy with product and service. Atera evidently make a lot of OEM roof bars for car manufacturers and to me they're as good as any Thule bar I've seen but significantly cheaper. They were rock solid with a roof box and 2 kids bikes on all the way to the Dordogne last year. They're also easy to fit once set up in position, they'll rest on the ST's roof rails without needing to clamp to anything and have a simple splined key to wind the clamp in so I'm pretty sure you could lift the whole lot on and off as one.
Edit: Just looked on Roofbox and it seems the Atera design (and price, up by ~£20) has changed since we bought ours just over a year ago so some of the above may not be accurate any more. I think at that price I'd be tempted by the Whispbars which are only ~£30 dearer now
A friend of mine just bought the cheaper Cruz Aero bars from Roofbox. They also seemed pretty good quality, the only thing I'd say is that the aluminium aero bar is very chunky, much wider in profile than my Atera bar to the point where he couldnt fit my old roof box that he was going to borrow this weekend as the roof box clamps weren't big enough to go round (and I don't have T bar fitment bolts for my roof box).