Some poeple like using "bingo" ink bottles, but I find those to be nothing less than irritating. So, I came up with my own storage container solution.
I use a double-walled plastic jar that I found at the craft store for around .70 cents. I also bought a new yellow sponge (probably found in the same isle as the jar) and cut it to fit inside the jar without being "squished" in the jar. I keep just enough Gamsol in the jar so that when I press the tip of my paper stump into the sponge the Gamsol moistens the tip of the stump just right.
I've found this method to work perfectly! If you're having troulbe with your current storage container, give this a try!