I go to winners and look at their mens shoulder bags or travel bags. They often have multiple large compartments to keep your barrels from dinging your marker, and smaller compartments for parts/allan keys/orings/lube etc. If they have a handle or shoulder sling i usually just cut that off to keep them small.
Typical cost is about $20 - $30 canadian and they make excellent marker bags.
If i get lazy i just use a dollar store neoprene laptop bag.
My coworkers were mortified when I told them I like to shoot people. They didn't know what paintball was.