That's the reaction I got from about a half dozen LBSs when I asked the same question!
I know there are sources, but I don't have their url's.
My favorite was the Shimano SIS housing. I even did a bike using their lavender
color! My Cannondale MTB has alternating red/yellow to match the paint. The colors offered at one time in SIS housing were the best! I even used the SIS housing for the brakes, just to get the right color.
and remember, the LBSs are NOT laughing AT you, they're laughing WITH you! .
good luck with that!