What variety are you after and what state are you in? Freighting snail would be a bit messy in my opinion as i catch them, house them for a day with lettuce then feed them to my lizards, but the container is incredibly messy after just one night. i would nt open the freight tub close to your face,yuk...
Is it possible to go for a walk around the neighbourhood after it's been raining and collect some? (Just keep them for a while with lettuce before feeding them to your bluey so you can be sure they've not ingested any poison.) Otherwise you could consider planting some lettuce or other green fleshy plants that'll attract them. They love hiding in damp, dank and dark areas.
If not, maybe someone here could ship you some snails?
Yes they are for my pink tongues as well as blue tongues and shinglebacks, we dont get any around here at all, even in the rain! Thanks for the advice, never thought of looking for canned snails other than those from the pet shops.