Are you sure you really need one? Most ESCs that have been manufactured in the last couple of years have either auto-sensing or programmable cutoffs that will pulse the motor or shut it off completely when it's time to land. Check to make sure before spending your hard-earned money on additional technology.

If you're running a 2200mAh pack, the plane you're flying must be something of fair size and value. Do you really want the motor kicking off on you at the worst possible time, leaving your valuable plane to the mercy of whatver bush or obstacle that may be underneath it?

Even if you do have a cutoff or LiPoly alarm, don't depend on it to tell you when to land. Use a timer, and keep the cutoff as a backup to tell you if there's a problem with the battery.