I always got mine on eBay, to be honest. Never paid more than $1/pair and they always held up at Burning Man, so....
These aren't cheap but they are beautiful. I have worn these for Fantasy Fest and she has made waterproof ones for me. Gina's Gems - Jeweled Pasties and Nipple Covers that Sparkle
A few pics might be a good idea for this thread. For starters check out the Dos Equis guy costume Stephie and I had for superhero night in December. He's a superhero for sure, but her pasties were spectacular! Stay Thirsty My Friends!