Bare minimum home networking
At less than $20, the TL-WR941N is great for those needing a functional Wi-Fi network to share the Internet access and not much else.
Underpowered but super easy to use
For less than $30, the D-Link DIR-818LW is one of the most affordable 802.11ac router on the market and it's quite fast, too. If you live in a small apartment, this is an excellent choice.
Cheapest cloud-connected router
If you want to easily monitor your home network while you're out and about, the D-Link DIR-605L is the most affordable option, costing just around $15. The router works well if you want to share your Internet connection with a few devices at a time.
A reliable router
For a cost of around $30, the Linksys E1200 is actually a great router. It's easy to use, reliable and has quite a few advanced feature to keep your home network safe.