After the dilemma with finding all the right clips for arch mouldings etc I just thought I'd show you what I've done with mine, at a grand total of about £6 to do the front and back arches (both sides) and 10mins with a Dremel I bought a pack of about 30 nylon M6x20 bolts complete with nuts and washers for about £6 off eBay I cut the head in half so it was about 1-2mm thick, and then spun them in a drill whilst holding a sanding bit against the collar to make the thinner shank part The result is that they grip the arch moulding cutouts without spinning, and even if they do on the odd one, you can grip the top of the thread easily and tighten them up. This means they won't go manky, they are easily removable, reusable, and very cheap.
It doesn't need to be as hard as obtaining all the right fixings when you can use something as simple as this. I've heard of some people are using number plate bolts for this, which must work in the same process, but they have a circle head with a flathead cutout so they'll spin in the moulding easier unless glued in place.
I've got loads of various BMW, Peugeot, Seat clips lay around and none really did the trick. I'm sure you could find some push-fit clips off another model that'll work but being able to remove and reuse them is handy I suppose
Anyway, merely an option more than anything.