Cableties are your friend!
But if you're too fancy for that, I guess the clips are something like this maybe (pic below, these attach the 'dogleg' sideskirt pieces on my Mirage), you could probably find something at pickapart that would work? A while back when I removed the doglegs I broke the factory clips, so when I went to reinstall I decided to Sikaflex them on. Big mistake, the next time I tried to remove them they were well and truly stuck. Took me forever to cut through the Sikaflex with string and a razor blade. Went to pickapart and pulled a bunch of white clips like the one below off a random car's interior door cards, they work fine. It's all about improvising.
Seriously though, cableties

if it wasn't for those god-given beauties, both of my cars would be nothing more than a couple piles of parts!