Wayne,
Save your money on the charger, the Onyx that you have will charge NiCad's and Nimh's. When you move on to flying electric planes, get the Turnigy Accucel-6 when you buy the lipo batteries and other stuff from Hobbycity.

I personally still like to use Nicd's because the voltage drop right after charging is less. I also feel that they last more cycles than a comparable Nimh. I usually pick them up second hand and cycle them a few times to see how they work.

Between the wall charger and your onyx though, you will have something that will charge your batteries for you.
Good Luck,
C