the tygon hose is cheaper at
USplastic than at
McMaster, however, you have to buy the hose in 10 foot lengths from USplastic (im not sure about McMaster).
Dtek Customs sells 3/8" ID tubing with 1/8" thick walls and 1/2" ID tubing with 3/32" thick walls for $2.65 per foot (which is 20-50 cents more than what USplastic charges). it is the R-3603 formulation. note that the 1/2" ID tubing only has 3/32" thick walls, so it probably doesnt have as tight a bending radius that 1/8" thick tubing would have. just something to consider if you happen to have some tight bends...