If the mesh system is out of your budget, you can just get a cheap wifi router and use it as an access point. You will need a network cable from your main router to this one, and then set it to AP mode. Then you can set the wifi to use the same settings as your main wifi network (but on a different channel).
I have used some of these to increase coverage. Much cheaper than a mesh system. Works great if you don't need high wifi speeds (just normal streaming/browsing, not sure how fast these will go).
Tenda's W-F3 offers 802.11n 300Mbps WiFi capabilities and is specifically designed for a small to medium offices and homes. It features bandwidth control functionality, quick effortless set-up and x3 5dBi high-gain, omni-directional antennas to ensure max
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