If your CVV shop lets you see the ZIP/postcode before buying it then all you need to do is go to a ZIP/postcode house price checker website such as
https://www.zillow.com/home-values/ or
https://www.zoopla.co.uk/house-prices/.
Check at least 10 and keep note of how high they are, eventually you will hit the person living in a $600k - $800k / £600k house who will have a good balance saved on their card, avoid low income non-freehold houses as these tend to be people who might have nothing on there, if it is a freehold house it means they own it.
P.S. Premier cards can only be obtained by someone earning $100,000/£75,000.