There aren't a whole lot of options nationally when it comes to canopies that can handle reef lighting.
Your best bet is to find a LFS that works in tandem with a local carpenter and sells their canopies and stands through the LFS; though you would still have to mount retrofit lighting yourself, unless the LFS is willing to do it.
Otherwise, check out custom aquarium builders. Alot of them also sell custom canopies and stands and could probably build one for you with lighting installed.
The only prebuilt type of lighting I'm aware of comes in black powdercoated hanging fixtures, and that doesn't meet your requirement of a walnut finish.