WiFi Amplifier Pro 300Mbps 2.4G Wireless with 2*2 dBi Antenna Wall Plug WiFi Extender Signal for Router - Walmart.com
Detailed Guide to Apple WiFi Extender Setup
How to connect Apple's AirPort Express to any router to make an AirPlay 2 streaming target | AppleInsider
TP-Link AC2600 WiFi Extender(RE650), Up to 2600Mbps, Dual Band WiFi Range Extender, Gigabit port, Internet Booster, Repeater, Access Point, 4x4 MU-MIMO Wireless Range Extender/Media Bridge - Newegg.com
Alternatives to Apple's discontinued AirPort routers - CNET
Apple AirPort Extreme 802.11ac base station Fast Wireless Extender | eBay
Apple AirPort Express 2nd Gen 802.11n Wifi Wireless Router Extender A1392 | eBay
Apple AirPort Express 1st Gen 802.11g Wifi Wireless Router Extender w/USB A1084 | eBay