Actually, it really didn't matter either way. This one just looks better IMO. The primary goal was to have two 2-cell banks (which are completely independent) in a smallish package.

Nice work on the chargers BrianG, you really are far too modest about your abilities. :thumbsup

How much did it cost roughly to do each one?

The first one was about $30, but I got a lot of extra parts, so it's hard to tell. The only thing I had to buy on the second one was the case ($7 shipped) and a switch ($3 IIRC); everything else was stuff I had.