I have an CNC3040 and it is very good for the cost. It is quite slow, but pretty accurate, enough for nearly any hobby job.

You will want to get a solid carbide cutter (end mill) to do any material harder than wood. I've cut 6mm aluminium panel on mine and although slow (6 passes @ 200mm / min) it did the job well. Carbon fibre is a hard material so don't push it, but I think it will manage with thin sheet.

Have a look at this site - http://www.easycomposites.co.uk/

You will also need a CAD and CAM program. CAD (like AutoCAD) draws the things you want to cut, and the CAM program lays down the actual cutter paths, cut depths and number of passes etc..