It's seems like despite the recent UCI ruling to allow disc brakes, almost no companies make a disc brakes CX bike. (Though I suppose it'll take some time to respond with new disc bikes.) I've seen one of bikesdirect.com, but that's seems to be all that's available these days. So is anyone out there riding them or looking to buy? The only guys I know around me either have one of the old Cannondales or set up a custom bike.
I think Salsa and maybe Voodoo have disc bikes. All of the bikes currently available were designed by summer of 2009, so there hasn't been time to design and produce a bike with disc brakes since the UCI decision. Even at that, I bet most of the manufacturers are waiting for a better(lighter) disc brake design as well as some indication of public demand. So, the weight of the whole thing probably rests on Avid to make a new bb5/7 design that will get enough people excited about trying it that bike manufacturers add disc tabs to their bikes.
I raced my Salsa for a few seasons setup with disc brakes, but decided the weight penalty didn't justify the gain. I still have the bike setup with the disc brakes it has just been retired to commuter detail these days. As you state I bought frame and fork and pieced together myself. I know there are a few companies that make them (add Redline to the list), but most of those are lower-end models with less desirable components.
I have a fully ghetto-ized single speed disc brake cross bike that I intend to campaign on. I know Soma, Salsa, Origin8, Voodoo and just about any custom shop will perv one out for ya. My dream would be a single speed Speedvagen or Soulcraft with discs. Crabon Fibre? No thanx. I just like discs as I have them on every bike I own save one road single speed and the power is noticeably different. I do not give a rats a$$ if its not pure old skool or wtf. Weight is not a huge deal to me as I am bigger cat and I like the way they perform.
It will be interesting to see how many folks actually convert to disc in the pros and higher cats. I guess if you're a pro and have lots of bikes you'd have a "speciality bike" with disc for specific courses.
I love my disc brakes on my mountain bike, but I just don't see the need for that much braking power in a cross race.
Most companies are probably taking a wait and see attitude. Discs have drawbacks with regard to fork weight/mfg, danger, etc...so if the pro's really want them, brake companies will make them but it's not a given yet.
I'm building a Major Jake frame with a Wound Up disc fork, so I'll still be running a cantilever in the back. You can never use that much braking power in the rear, and the canti is lighter, so it might be a good combination.