For those who *don't* fly, most fuel tubing is 1/8" surgical neoprene. If you only want a short length, most hobby shops that handle flyable models should have it at an obscene markup. Medical supply houses sell it by the reel but that's mass overkill unless you're a hobby shop.

Surgical grade tubing is reasonably photo stable, and on a model will fail due to nicks and cuts long before light degrades it. I have no idea about inner tube material. If you're seriously concerned by light stability, I'd just bend the whole thing out of a decent size length of music wire.