It is easy to replace, you can just replace the inner cable or the cable and housing. You can get the generic brake cables at the local bike shop for $3 - $5.
http://bicycletutor.com/adjust-v-brakes/
http://bicycletutor.com/lube-brake-shift-cables/
http://www.amazon.com/s?ie=UTF8&rs=3403201&ref%5F=sr%5Fnr%5Fn%5F0&keywords=brake%20cable%20housing&bbn=3404731&qid=1234993983&rnid=3403201&rh=n%3A3375251%2Cn%3A3403201%2Ck%3Abrake%20cable%20housing%2Cn%3A3404731