yeah, switching from drop to flat bars means new brakes and shifters and cables ... unless you have that stuff around (and the right gearing, and brake pull type), it gets expensive
btw, folks I know with cyclocross bikes that they use for non-CX purposes tell me, the CX tires wear out pretty fast on pavement. I take 700x32 touring tires on all sorts of easy dirt on my hybrid. also, a true CX bike is race oriented, won't have fender or rack mounts, and other niceties.