$5 is pretty cheap.. does it work well? I got mine from http://floatswitches.net/ works pretty well... i replaced the battery with an old 9v DC cell phone adapter....

I only wanted it so i could keep my res on the same level as my grow buckets (DWC 5 gal buckets) and avoid the gravity fed float valve... with electronics there is no way it can flood...

well - there still is - you need some kind of anti-syphon device... i just punched a hole in my vinyl tubing and stuck a piece of the WD-40 straw (nice and sturdy) in there so that air can fill the tube in the event of negative pressure which would USUALLY make all water surfaces level... ie - flood your grow room.

EDIT: the straw contraption - is INSIDE the res.. near where the water will leave... when the pump is on - a tiny stream of water shoots out - so if you do this, make sure it is over water. (in the res, or control bucket)