Yay Ali! It sounds like you're buying them from a bricks & mortar store instead of online, which is a really good idea. The sizing is a bit odd and if I'd bought online I would have ended up with the wrong size shoe. The great thing is that you'll have a chance to try them on before buying them too. I knew the moment I put them on that they were brilliant. It helps ease the pain of parting with so much money for a pair of thongs!
Another good thing about them is that they're brilliant if you have wide feet. They're designed for the wider European foot so they fit really well for those of us with chubby little trotters!
While out for a walk in St Kilda the other day a woman overtook me while walking her dog. I wasn't walking at all fast, and she was really power walking, but I was a bit miffed because I thought "Hey, you can't outwalk me while wearing bloody thongs!" Then I looked again. Yep. She was wearing FitFlops too! So there you go. The word is spreading!