I don't know if any of you done this, but I was in a bind this weekend at the Meet 'N Meat contest.  My starter battery just went completely dead and I could not get to a Hobby Shop.  So I hook up my 3s(11.1v) 2200mah Lip0 which would give me close to the 12V I needed for my power panel.  You may ask "Why do you even need a power panel for CL'".  That is because I am flying a 1/2a model - actually is a .061.  Since I was only using a 1/2a type starter, I felt very comfortable that I would not drain it beyond the low voltage limit for a few starts.  

I am wondering if I could just make or find a LOW COST< $10, "Low Voltage Cutoff" curcuit without have to purchase a entir ESC/BEC for this purpose?

The other cheap alternative is to use one of those $5 LED voltage indicator that a lot of you already have, connect that into battery balancer curcuit with a test switch.

This will work. http://www.hobbypartz.com/fm23-1416.html there are many others. Helicopter pilots use them as they cant exactly have their speedcontrols shut the motor down in flight.

If, after all that, you still want a low-voltage cutout, I'll send you a free schematic.  Free of charge and free of any significant testing, that is.  It's a pretty simple circuit, but the way things are these days you may well have to buy some parts mail order.

Basically you need a honkin' big transistor (or a relay) to turn things on, held on by a comparator that looks at the battery voltage and shuts down when it falls below your desired threshold.  Or maybe just a voltmeter and a brain, plus a fuse in case you short something out.