I couldn't imaging you could get that coverage with 2oz of paint. Of course I've never measured out paint, so 2 oz. must be more than I realize?
I use this stuff to airbrush with you can get a lot of coverage even with a mini foam roller just have to thin out the paint a bit as it's fairly thick out of the bottle if you thin it out to say a pepto bismol consistency you effectively almost double the amount of paint you have in the bottle. Adhesion to glass is very good as well as plastic and wood. It has the added benefit of being non-toxic as well clean up is just warm water and a lil dish soap if needed.