Kevin719 This approach is risky unless a really good return policy is in effect. The for-sure-safe way is to buy from Google. In the U.S., people have reported success buying unlocked Pixel devices from Best Buy. There are also positive reports about Amazon purchases, though there you would be relying on the return policy because it's always at least faintly possible that what gets shipped to you is unrelated to the listing you carefully scrutinized.
The flip side is that if you are willing to run some risk of hassle (potentially including waiting weeks for a refund) probably some secondary-market "unlocked" devices really are unlocked, so some people probably can save some money.
Another thing to be wary of when purchasing a high-price item for a low price from an online seller is that the item might have been stolen from somewhere in the supply chain, in which case the IMEI might have been banned, in which case the phone won't work with any carrier even if it thinks it's unlocked.
As the saying goes, "caveat emptor"!