I just thought I would let everyone know about this alternative for extra tubing. 100ft for $9.95 on Amazon (about $.10 a foot compared to $0.35 @ pet supply shops).
Home Depot and Lowes has it for $.06 per foot, and you can have it cut to whatever length you want. You can get a softer, flexible tubing in black or a more rigid, white tubing. They also have connectors and valves, pretty much everything but the misting heads.