Are you interested in a ready to ride bike or build it yourself. You can certainly get the frame you desire any number of places. I bought a Kinesis Decade Tripster on sale from ProBikeKit in the late summer and built it up with a mix of mountain bike and road components. Disc brakes figured into the plan as did 26" wheels and 1-3/4" tires.
I have a pic and breakdown of the cost here.