There are a lot of folks at our local track using the Onyx 230. It seems to be a pretty nice charger for a good price! The Dynamite AC/DC Lipo charger is a little less expensive, but does not have a read-out to see the status of your battery. For the $20 difference, I'd go with the Onyx.

The importance of balancing really depends on the quality of your packs. I have a handful of Orion/Kokam packs as do most of my buddies. These packs never seem to be out of balance. The Yeah Racing packs are a whole lot cheaper but the quality would come into question. So if you are getting these packs, I'd definitely recommend a balancer... that's going to be about another $40.... Just remember that if your LiPo pack becomes grossly unbalanced, your pack will go downhill quickly. Once a pack is damaged by overcharing a cell there's nothing you can do... and doing it once can ruin it.

Good luck!

Jerome