ComegaCity via Amazon.com has the Intel Wireless-Ac 9260, 2×2 Wifi card for $11.95. This is the lowest price I’ve seen.
I bought this recently at around $17 and replaced the 1×1 card in my Lenovo S340 and it roughly doubled my wifi speed. It also upgraded Bluetooth to 5 (I think stock on my Lenovo was 4.2). I just bought a second card for my wife’s laptop.
https://www.amazon.com/gp/product/B079QH5KW1