Comment No need for black market. (Score 1) 63
Used routers that can run FOSS router software abound because factory firmware updates ended though many are amply fast for their real use case. I just flashed my old 6700v3 with FreshTomato which is simple to do. I'd upgraded but kept the 6700v3 as a ready backup. (I don't believe in being one-deep on comm gear including computers.)
Of course any PC with two or more NICs can route and there are plenty available. "Home lab" enthusiasts make all sorts of interesting appliances from tiny PCs with ethernet and wireless with space to add a second single or multiport network card.
Routers are computers after all.