Google's Nest Wifi system is designed to work as a set, but if you'd rather assemble your setup piecemeal, a single router works just fine on its own. Today, you can grab an individual Nest Wifi router from Woot for $130, $39 under the normal going rate.
One router covers a respectable 2,200 square feet. That's nearly the median household size in the US, so with optimal placement, there's a good chance a single unit will work for your whole home. But if you need to expand after the fact, it's a breeze — just grab additional points and set them up in the Google Home app.
The router is being sold through Woot, so shipping is free for Amazon Prime members. Otherwise, you'll have to pay a few extra bucks. This price is good for the next 10 days or until stock runs out, whichever comes first.