There are plenty of places online to purchase a didgeridoo bag.

You can always try eBay or one of the fine stores listed in my links section.

Here are a couple of alternatives.

My friend Brian uses ski holders / bags to hold his didge’s while traveling.

What I did is purchased unique cloth at an import store and had somebody hand tailor it, for a total cost of $75 which is just a bit more than I’d pay for a good carrying bag online. Except, that this case is personalized.