I found a pair on eBay believe it or not. Just research how to spot a fake one, and closely examine the pictures. If what you receive doesn't match the pictures, eBay has buyer protection and you WILL get your money back if you receive a counterfeit. I ordered a pair off eBay and they're authentics, and I've subohmed them down to .32 without trouble
In fact, I just picked up another pair on eBay. That'll bring my collection to a total of six VTC5's