Shenzhen can get you anything, for a fantastic (very low) price. If they don't have it, they will make it for you. I can't speak from personal experience (I have never been there and I don't buy counterfeit goods, as I like to foster innovation and quality), but there are ample stories of the supply available at Shenzhen. However you probably need to have an interpreter (it is not like HKG). I've always found everything I want to buy in Kowloon and have been pleased with both quality and price.