I went through this last year- the mounting kit is a lot more than a few snaps!....
I won a virtually new tonneau on Ebay last spring, minus the mounting kit. When no amount of begging (about a dozen calls to Audi) would convince them to sell me the parts I needed, I took advantage of my local dealers' "30 day return" policy, and ordered a whole new tonneau kit so I could see exactly what I was missing. The mouting kit is fairly extensive, and duplicating it was a huge PITA! Fortunately, I know the owner of a local metal fabricting shop who was able to make me an exact copy of the mounting bar that fits across the back of the cockpit, but locating the correct Tenax fasteners was almost impossible- I finally talked a Tenax specialist into ordering some from Germany! Then there's those little Velcro backed discs.... anyhow, I finally got the thing mounted, and returned the factory kit to the delership (on day 30!), and have been enjoying it ever since. The thing looks and works great, and I use it constantly, but I would NEVER go that route again- I ended up having almost 400 bucks in the project, and more hours than I care to count. My suggestion to anyone who is considering one of these is to find the best deal you can on a COMPLETE factory kit, install it in an afternoon, and go have fun!