Hi, There are always Reptile expos and shows that are scheduled in many states, throughout the year.
Great place for him to handle learn and meet reptile people. And buy a neat lizard too ! 
I think the next one is :
Feb 28 2004 through Feb 29 2004
Unique Animal Expo and Pet Fair
Every month there is an new show in a another state.
Also you could depending on where you live, contact your local zoo. Ask to speak with someone from the reptile dept. Tell them about your sons wish !
They may be able to help you, or atleast suggest places or people, where you could go and visit.
My wish is that your son gets his wish, *SMILE* and everything turns out wonderful for him as well as you.
Take care, and let us know how you make out ! 
Eve