dont get it from McMaster, get it from
USplastic instead; its cheaper ($2.91 / foot of 1/2" ID 3/4" OD R-3603 tygon). the only prob with USplastic is that u have to order in 10' lengths (so unless you need more than 7' of tubing, it might be cheaper to get it from McMaster if they sell in shorter lengths).
Dtek Customs also sells 1/2" ID 11/16" OD R-3603 for $2.65 per foot. a good 50 cents more expensive than USplastic, but it'll still be cheaper if you only need 7 or less feet of tubing.