The price.. good Lord
At first glance the price does indeed seem expensive. However, when searching
online for the price, it seems that this router is sold new for at least 139
dollars, so minifree's product is competitively priced.
https://www.cnet.com/products/netgear-n600-dual-band-gigabit-router-premium-edition/prices/
I got mine for less. Of course I did install librecmc myself, but it wasn't
really hard.
I'm guessing you only replaced the router's firmware (e.g. via the browser
interface) without the bootloader. The minifree version will also contain a
free bootloader (uboot) unlike the manufacturer's version.