I believe you're talking about official Walt Disney World merchandise. You can get them anywhere in the Orlando, Florida area--not just at the park and Downtown Disney. If you're talking about security cameras, try Amazon.
Walt Disney World camera are usually used to record hidden events and fun facts. Various camera brands are easily available in all the theme parks you visit. it will not an easy task to find one in a theme Park. After all, you need one probably in these theme parks when you make a visit.
