I see the last time this was discussed was over 5 years ago, so I apologize if it is old news. I tried all my existing banjo cases and the only case that fits it in the house is a guitar gig bag. Not so bad but it seems a little too thin and flimsy.
I see that the Boulder bags are recommended for some banjos but the dimensions seem to be too short (39 x 19 x 22 inches) for that longish Boucher headstock. The banjo seems to be almost 42" long.
If you can find a new one on Amazon, I believe you might be able to return it by asking the seller for a printed return label (paid shipping) if it doesn't fit. Worth investigating, be sure to review the seller's return policies.