Open Source WHM Web Hosting Control Panel Manager

im started some websites with cpanel on my linux server, i have it going, i been doing some research on a front end application called WHM which allows you to signup customer automatically and creates an account all in the cpanel. but when i saw the price for a license, my head almost exploded, abviously i can't afford it, do you ever heard of an open source GPL/UGN scrip in PHP which i can use for cpanel as a front end control panel manager? if so, please help me.