I just used these for my family trip and loved them. If you put the battery in backwards, the fan blows backwards. It took me a second to figure out why one of our fans was blowing the wrong way.
I do recommend that you tape the battery cover shut. I didn't last year and we lost two covers. Used duct tape this year, lost none. They really help with the heat.
I bought the Misty Mate 2.5 at Wal-Mart today for about $8. They're in the hardware section (not camping?). I tested it out and it works great. They are the size of an electric toothbrush. The fit in my kids' fanny packs too! It would be nice if it had a clip or hook on it.