Any laser power over 5mW can be dangerous, but like styro said you can also still be safe with a 30mw without safety goggles if you use common sense.
On the other hand, most people start with a low powered laser but eventually end up with high powered ones. Why not invest a little extra in some goggles I'd say, maybe you don't need them for a 30mW, but it's likely you'll be getting something more powerful in the near future anyway.