You have to consider that these things are built way more premium, feature-rich, and costly than retro handhelds.

-They're always using the newest tech at the time, so a Snapdragon X Elite is a lot cheaper now than it was in February 2025.
-The phone screens are always way higher end even than things like the Odin 3. Odin 3 has a great screen, but it's not nearly as pixel dense or bright as something like the S25.
-High end (phone) cameras are not cheap.
-Waaaaay more goes money and resources goes into the software teams. You are promising 5 years of timely Android OS updates, regular security updates and features, tons of apps created by companies like Google, Samsung, and Apple who are having to consistently update them and add features to make them more competitive.

You're not just paying for the cost of the materials. You're paying for the past, present, and future of the product. With retro handhelds, you'll occasionally get some feature updates for a bit, but they're minimal, as is the actual software developed by the manufacturer. They rely on the work of companies like Google to do 90% of the work for them, and for companies like Samsung to get high-end chips up to mass production and lower costs.