Well, it looks like an antique demijohn carboy, which can go for quite a pretty penny. Any large glass jar like that would probably be pretty expensive and they could break in transport. I would go for a smaller, wide mouthed bottle or jar that would be easier to find and preferably local.
I have found some pretty good instructions on how to make bottle gardens, too. I don't know where they got their bottles or how much it would be to get them, either since they're in the UK.