The big problem with fuel lines is that since most cars are now fuel injected, most hose in the size we want is of the amour ed type to cope with high pressure injection pumps. The additional stiffness makes it very difficult to persuade the hose round the tight curves needed on a bike and there is also the small problem of fitting hose between the aircleaner and engine casting for those with clamshell aircleaner housings. I've found that you can get the older type hose from suppliers, but it needs to be ordered and there is a wait, in the interests of avoiding liability claims the local auto parts shops seem to only carry hose rated to 50psi, which is too big and heavy for us.
My one time solution was that quite accidentally i found a 3' length of hose that looked about right in the local "Hose doctor" outlet with a price tag of $15 on it. I asked if it was petrol proof to which the sales guy laughed and said "that is everything proof" what you have in your hand is the end of a roll of silicone hose, which if were were to continue to carry the stuff would cost you about $100". It's been in place now for 3 years with no deterioration - I'm happy.