There is a significant difference between being sponsored and being a Rep. The above answers go for being sponsored, (although I think the statement by rcjon is a little exagerated )

For being a Rep, you just have to approach the company you want to Rep. Most if not all of the companies have a restriction on which helis you are allowed to fly in public if you are a Rep. Being a Rep, you have a discount on Parts and Kits, but is nowhere like being sponsored.

Rafael