About the gsm maybe u should check
http://code.google.com/p/sserial2mobile/
and if it has to be a module, i think this 1 is 1 of cheapest, i might be wrong
http://www.cooking-hacks.com/index.php/arduino-gprs-module.html
About the gsm maybe u should check
http://code.google.com/p/sserial2mobile/
and if it has to be a module, i think this 1 is 1 of cheapest, i might be wrong
http://www.cooking-hacks.com/index.php/arduino-gprs-module.html