Caudata.org might be able to help you. There are lots of people there who are trying to breed all kinds of salamanders/newts and they can answer all your questions. I know there are quite a few of them who have tiger salamanders. The reason you can find then in the UK is because they are considered exotic over there but here in the US its a natural species. A lot of the states won't let you keep a native species or allow you to breed them. For example, here in RI I can't keep a marbled salamander because they are a native species and protected whereas I've talked to people from other states where they can have them without a problem. You should check NC's environmental department. There must be a website. Do a google on tiger salamanders in North Carolina. Maybe you'll find something. Good luck!