You mean the roof hold down clips? If so, yes they are very expensive, but they are also crucial bits of kit and, having dismantled a broken one,(well, I had to have a look...) they are well engineered. I suppose they are also not made in huge numbers, which doesn't help (economies of scale, etc., etc.).
Luckily, having had ours break on our first journey (due to our not knowing and the dealer not ensuring the front ones were tightened up), the dealer replaced them for free...