In the USA I have used Swappa. Right now I have a Google Pixel 3. Brand new, it was too expensive, but I waited until both the Pixel 3A and Pixel 4 was available, then checked used and refurbished models. I found a Pixel 3 in very good condition. It didn't have a charger or a case, but I got both. Total price for all three was about $320 shipped directly to me. The price of the Pixel 3 alone was around $260-270.

Support for the Pixel 3 ends later this year, but I've had two years of very good service. I may keep it slightly after support ends to give later models an opportunity to become less expensive. Pixel 4 and 4A can already be purchased from Swappa for under $300; the Pixel 4 is scarce; it was not a very successful model for Google so very few were sold. The Pixel 4A is in plentiful supply and already in the same price range as the Pixel 3 was. The Pixel 5 is still selling used for $500+ except if someone sells a scratched unit; those go quickly.

For more modest phones, a reseller or used service, especially a solid one like Swappa can be a good source for less expensive, higher volume phones too. I hope that gives you some ideas, even though the Pixel models are probably too expensive.