50 cents - circulation

Please feel free to remove this post if it doesn't fit into this subreddit.. was looking and didn't know where to ask.

I recently moved here and have been trying to find the 50 cents coins - ones from the years when they were still in circulation and not the ones in sets since. But no luck so far.

Any idea on where I can find some without paying premium? Can I ask in the banks if they have some? Any advice is welcome.. thanks!!