I currently have a 7 speed STX-RC hub that I want to upgrade to 9 speed. I am thinking that i can do it for under $150.

I figure I need:
1. Cassette 11-34
2. Shifter Grip shift
3. 9 speed Hub Body
4. 9 speed Chain

I know that I should use a longer axle, but I am pretty sure I can make it work with the one I have.

Anything I am missing?