If tygon is truly what you want, a good local hobby shop should have it by the spool in different sizes even. It's what is used for fuel line on gas powered rc vehicles. Most of what they'll have will be silicone tubing for nitromethane, a more common rc fuel, but a reasonable hobby store should have tygon for gas use. Additionally, home depot and/or Lowe's sell some bits of tygon tubing for lawn equipment. But not as cheaply or by the foot like a hobby store would i think.