I can’t imagine inputs are very high for this, at all.
The tooling for the cartridges is probably only a few bucks a unit at absolute most. And most of that is in plastic injection molding. The entire 2600 memory stack can be condensed onto a microscopic IC these days as they werent more than 64kb in bank switching, and bringing the already developed code over is an intern's weekend project.
This is a massive nostalgia-powered money grab.