There are people out there making new NES games and selling them on real carts. They go for about $40; obviously they don't typically include ARM coprocessors. Sometimes they have blinkenlights though.

https://www.retrousb.com/index.php?cPath=30

I'd pay somewhere around $50 if it included box art and everything. I don't imagine that's quite enough to turn a profit.

I'd pay $39-49 because it's really cool.