i use 4-5 tubes 2 or 3 inches in dia. i still have the origional tube thats 6 years old, they last a while. i store my CTO, CTB, +green, neutral Denisity, and diffusion in separate tubes. works well, i can through all the gells in with my light stands and let them all bang around. i probably have 5-10 gels in each 2" and 20+ in the 3" CTO tube. i think my total cost was $15
i bought a lot of my gels from a store that kept them in shallow box drawers that seems really great if you are going to keep them in a studio.
i keep small 10x12s in a expandable accordian w/20+ divisions for each filter/density briefcase thing from officemax . perhaps make a larger one.