Anyplace that sells boat parts. If you have an exposed portable tank you can use the cheapie grey stuff. But if you have a semi permanant tank you really want to use B1 rated fuel line.
Looks like a piece of the correct diameter marine fuel line would work there, doubt that radius shown in photo would require a molded hose. Looks like an easy fix. Good Luck!
it once was flexable, due to time, useage, and fuel it is now hard or molded. any fuel line with the correct dia. will work fine, may be hard to get it where it needs to go. looks like the old hose has expanded alittle. put a little wd40 inside new hose just where it needs to slide on fittings, you will be good to go. good luck!