http://www.buy.com/th/interchangeabl...y-charger.html

This site offers 30 identical appearing li-ion battery chargers for
sale at $79.95 each. Is this overkill? Is there one li-ion battery
charger that can charge any battery with a few tweaks or adjustments?
How interchangeable are the battery's from different devices and
manufacturers? Please educate me on this subject.