I would go with a reptarium or a screened cage. A lot of people use smaller cages for baby chams. This can make it easier for the cham to notice their food. It is very important to have your reptarium or screened cage completely setup and tested before bringing your new cham home.
Most pet stores sell small screened cages that I prefer over the reptarium. They are made by ESU:
You will eventually want a larger screened cage. These are available online.