WTB rock for small tank - any help greatly appreciated

[Fish]

Hi everyone,
I am wanting to buy LR with an interesting shape to put in a 8" cube. A single rock or a couple fist-sized pieces would be awsome. I was thinking of doing a pinacle-type formation in the center of the tank. Will also buy base rock that I can break into rubble for the filter. About 5-10 lbs total?
I finally got an office and a desk at work and my boss said I could have a small fish tank - he was probably thinking like for a betta or something

I appreciate your help!

- Chad