Time For The Tooth Fairy

My oldest son, Ben, has a loose tooth, with his new one coming in right behind it.  It hit me that my little baby is now a kid.  He starts school this fall, and it seems like he is growing up way too fast.

As hard as it is for me to watch our kids get older, my wife is having an even harder time with it. 

My parents are taking Ben to Florida for two weeks, and my wife is really struggling with it.  When I called her yesterday to tell her about Ben's loose tooth, she almost broke into tears.  She told me how mad she would be if he lost his tooth while on vacation.  I promised that we'd get it out before he leaves.

This the first time that one of my kids are dealing with a loose tooth... enter the Tooth Fairy.  So my question is, what's the going rate for a tooth?