If you've checked discount, tire buyer, simple tire, Amazon, Walmart, Costco, and tire buyer you've covered basically every tire distributor/warehouse in the country.
Finding a set after that would have to be a specific shop or person who just happens to have 5 on a shelf.
Good luck. I waited for 4 mos, and found a used set on FB marketplace. The person selling them had access to a new set, and I bought the last 4 that particular warehouse had a few weeks ago.