Came across the following quote by Arthur Ashe (tennis player):
Start where you are. Use what you have. Do what you can.
I think that's a great way to approach carving. The world is full of the next great tool you absolutely have to have in order to be a better carver. Lets face it, many of us have the tool collecting bug anyway. That doesn't mean you can't start right now- If all you have is a knife, get some wood and go for it. if all you have is $20, get a knife and some wood and go for it.
Maybe you're a whittler and that's all you need. If not, you can always get more, later.
Just go for it (Don't tell Nike I said that)