Im thinking about renting a storage space for my band to practice in but none of them have outlets. I was wondering if I hooked an outlet up to where the light is I could plug a power strip up their and hook up two guitar amps and a light. Will this trip the breaker?

You more than likely will trip the breaker by doing this. This is mainly the reason why storage places do not have adequate outlets. This also prevents people from living in storage units as well.

Guitar amps don't draw that much current, 100-200 watts in my experience. So as long as the breaker is not already maxed out you should be fine. They make devices that screw into a light socket and give you outlets.