Hiding in plain sight.
The Stalwart A200017 lock box with key diversion book safe is down to $9.41 on Amazon. This lock box normally sells for around $14, and even though it has dropped from that price before it has never sold as low as this.
It's a $10 safe, so it's safe to say if it gets discovered it won't take long to get inside. Its biggest security is in its unassuming nature and the fact that no one reads dictionaries anymore. I probably wouldn't keep anything absolutely irreplaceable inside, but it could be a nice place to store a few extra bucks, a backup flash drive, or a two-factor authentication key. It comes with two keys to open the safe, and the inside storage measures 2 x 5.625 x 9 inches. Users give it 3.9 stars based on 244 reviews.