Best lens for Nikon D3100?

I'm looking for a second lens for my Nikon D3100. At this point, I take portraits outside of people/babies/families/couples. Maybe looking for a wide angle lens? Wanting to stay under $300, if that is possible.

Any suggestions?

Have a look at AFS 50mm f/1.8G, sooner than later you would like to have a 50mm prime in your kit.
The other option, in telephoto would be 55-200mm DX lens, DX is cheaper and lighter than FX.