So, I guess I'm going with OSB. Is the the quarter inch too thin or should I stick with half inch? Also, any suggestions on economical insulation? Here is a pic of the shed now, so you can see what I'm working with. I am waiting on the metal shop to finish with my roll up door, then I'll start with the walls.

 

I don't know about humidity where you are but with a metal shell I would consider rigid foam insulation.
It won't absorb water and become soggy inside the walls and against the steel.

Just my 2c...

 

Alabama...humidity doesnt dip below 90% very often...we have two seasons: the humid and really humid.

shane

 

On interior non load bearing walls i like using steel track, and then infilling with wood studs. gives you the speed of steel and the cheap cost of wood.

If your worried about moisture just use 1/2 OSB and paint it.