I have a recommendation - if you have never come to a Dragon before (and even if you have):

1) Go to Walmart, Best Buy or Sams' Club
2) Look for "FRS Radios"
3) Buy one (or better yet, a set of two. Even better - a set of four)
4) Get four extra batteries for each radio you buy
5) Be willing to share with someone who did not read this post!
6) Go back and get four more extra batteries

Or... go here: https://www.google.com/#q=FRS+radios...w=1760&bih=813

Any Portable FRS radio will work, some better than others - but any radio is better than NO radio.

I expect to lead a group, so I intend to bring at least two (so that at least I and my last car have one - but truth is, sometimes we need better range than these radios give, so we need one or more cars in the middle to relay, at times, especially in a LONG line of cars and with over 60 cars - we may have some long convoys.)

You will know more what is going on (usually) and can get answer to questions faster and hear crazy comments as we roll along!
Also, the leader and last car need to be able to communicate so that we know all cars got thru the light !!!! (This way, we know enough to wait up if someone got caught by a fast light).

Radios are probably the most common, "Wish I had thought of that" item at the Dragon.

You can usually buy batteries at the 'Gap or in Robbinsville - most of these use AA batteries - but you'll pay less at WalMart or Radio Shack.

MY personal opinion is that rechargeable batteries and chargers are a waste of money for those who don't use the radios a lot, if anyone was going to ask.
But it's up to you.