DIY Eero solution?

So, frequently I'm asked by friends and family how to improve their networking setup, and more recently in my case, I've battled with making the most of my new Fibre connection with the poor ONT location chosen by a previous tenant. But in the case of family, one case has become so bad that they've given up on local help and asked me to come down to Hastings and help them out over a weekend.

Something that's caught my attention recently, was the smartly presented, simplified eero WiFi product that just launched which builds a "mesh network" effectively a collection of range extenders, offering one fast, unified Wifi network throughout a home. But at $499 US + shipping, it's a bit out of reach.

So, I ask how you would build out a network (with which products) throughout a home that offered a similar experience, but at a more affordable price?

In the case of my family members, I'll be looking to find options as follows;

A powerline kit for a fastest possible fixed connection in one other location

A WiFi range extender, as opposed to a seperate AP, to maintain just the one SSID

2-3 locations throughout the home

I suspect that TP-Link's Powerline with wireless extender kit could help with that (does it extend the same SSID via the powerline as expected by the phrase extender?)

Cheers