I'd watch out for a couple of potential problem areas with a production CX bike. It's cheaper to buy the whole bike, but it's also possible to build it up from a frame. These are my personal issue, if you will, some people will disagree with one or more.
(1) Make sure they don't cut the stem too short when you buy the bike, if you like your bars roughly even with the saddle.
(2) Make sure gearing is low enough. Some CX bikes come with doubles, I don't know of any that have gears low enough for me to be comfortable touring. I want a low gear of about 20 gear inches; that requires a mountain triple crank and pie plate cassette. Bar-end shifters can handle the front derailer, you have to be careful with (road) brifters.
(3) Does it have eyelets to mount racks and fenders? OK, you don't have to have fenders, and you can probably mount a rack on any steel frame and fork. Just don't try it with a carbon frame, and if it has a carbon fork, be prepared to go without a front rack.
(4) There should be room for fat tires (say, 700C x 32-37), with fenders. Probably isn't an issue with CX, but check before buying, or be prepared to stick with smaller tires. I've had a problem with horizontal dropouts (which many CX frames have) with a bigger tire. No fun putting a wheel on flat because it won't go on full, pumping it up, and finding out THEN there's a leak in the replacement tube.