If you're okay with used, I got an "industrial" mini PC with loads of connectivity for maybe $125? https://support.onlogic.com/product-documentation/industrial... And there are plenty of configurations at lower prices, as well as many other manufacturers in this space.

Banana Pi makes SBCs with lots of networking ports.

Not sure if this counts as low cost... https://store.minisforum.com/products/minisforum-ms-r1-works...