Currently the best place to buy hermit crabs is from pet stores. Small stores have a better likelyhood of their crabs being treated humanely as large chains often have poor conditions.
Mall kiosks are usually a very undesireable place to purchase them, as there is often very little in the way of supplies for your crabs and there is also a good chance they have been in very poor conditions leading to ill or permanently damaged crabs that will not live long.
The same for tourist shop and beachfront strip malls. If the crabs have been kept in a wire cage (which is very common in these kinds of places) and exposed to the air and temperatures, the chance is they will die rather soon, usually within a few weeks of purchase.
Make sure to research the proper habitat, temps, humidity, and feeding and water treatment for hermit crabs before you purchase them. Do NOT depend on pet stores to know what you will need, they are often very uneducated on the care of hermit crabs, and their job is just to sell you "stuff". Most of the "stuff" available in pet stores for hermit crabs is not safe for them, and not what they need.
Visit the crab care section at a reputable forum website where very experienced crabbers frequent, such as http://www.hermitcrabparadise.com or http://www.crabstreetjournal.com
yes
no they could but they don't
Pet stores
A lot
No, Hermit Crabs are omnivores.
Yes hermit crabs have antennas.
fish and bigger hermit crabs
No hermit crabs are small and friendly
sea birds, fish, octopuses, crabs, and other hermit crabs
in seragoon north got one shop sell very small cute and cheap hermit crabs
it deppends on how big the hermit crabs and the moon crabs are but if the hermit crab is bigger youv'e got your self a dead moon crab
no i had hermit crabs and had salt it didn't hurt them