For good WLAN, I generally recommend a WiFi mesh system. Everything else is a tinkering that does little or nothing. Extenders are outdated technology and cannot improve a WLAN. You can save the money. The advantage of a modern mesh WiFi system is that you can move freely in the area of the WLAN reception and the devices always select the best transmitting WLAN mesh router without interruption. A good mesh WiFi system does not have to be expensive, e.g. the one from Xiaomi is very good and costs less than 130 Euros:

Xiaomi AX3000

There are also models from other manufacturers, but they are technically less good and sometimes even cost much more.