The Google Wifi system is nearly four years old at this point, but it turns out that a competent home Wi-Fi system from 2016 is still perfectly good to use in 2020, especially with the updates that Wifi has received. Costco is currently offering a Google Wifi 4-pack for just $229.99, with the only caveat being that you have to be a Costco member.
Don't let Google Wifi's age scare you; because of its Google integration, it's painfully easy to set up and use, and it's still better than many other mesh systems on the market today. Looking at Costco's photos, it seems to be the slightly revised model that Google released a few days ago. Changes are limited to a very slightly revised design with a new barrel jack adapter for power; the internal specifications are all still the same. If you need to add more units down the line, Google Wifi and Nest Wifi units can be used in tandem.
Costco is asking a very reasonable $229.99 for this 4-pack. For comparison, the Google Store only sells these as 1-packs and 3-packs, so you'd have to buy a $199.99 3-pack and a $99.99 1-pack to make a package of four. That'd run you a hair under $300, so consider this a $70 discount. Shipping is free, and there's a limit of 3 per Costco member.