€55

Here are three used Netgear wi-fi 'range extenders'.

Simply plug the extender into a mains socket (standard 3pin plug) at a mid-point between the broadband router and the kit, configure the box (instructions online) and off you go.

Buy all 3 for €55 or will split.
2 off N300 / EX2700 units (with mini-aerials, 2.4GHz only) €20 each
1 off AC1200 / EX6110 unit (built-in aerials, 5GHz plus 2.5Ghz) €25

Postage extra at cost - or collect from Bantry, West Cork.

The N300's also have an RJ45 network socket, so they can connect to wi-fi or wired devices.