I sell them 10 at a time and whatever size you need. Dubia are not very good at escaping anything. They are very easy to keep. You could just keep them in a small critter keeper with a few pieces of egg carton and food.
Yea i'd say buy them from someone online.
James is good, or i can sell them to you in what every size and amount. If a pet store would have them for sale they would be very expensive. Plus if they breed and you have too many just sell them off, heck i'd buy them from you for cheap.