I switched to a Kona Jake CX bike this year and have been really enjoying it. I had previously commuted on mountain bikes and a hybrid. My commute is about a 14 mile round trip, mostly flat but with some short, steep hills. I had no trouble fitting fenders, rack, and panniers to it and have also used it on numerous shopping trips, etc. I even rode home with a 50 pound sack of cement on the rear rack, though it was a bit of an effort to pedal up out of the river valley. Some lower gears would have been nicer on that trip.

The 2010 model retail price is $900.00 US but I picked up a used 2008 in good condition for $650 canadian. All of the 2010 entry level CX bikes I looked at were in the same price range. You might find one of last years models on sale and closer to your price range. I also looked at the Specialized Tricross Triple but it has Shimano 2300 components compared to the Tiagra on the Kona. On the other hand the Tricross DOES have a carbon fork.

I'm not a racer so I can't speak for the Jake's suitability for that purpose, although when I was researching it I read that others consider it adequate for a CX beginner.