You may find some sellers on this site
[1] [2], I cannot confirm that you will not be scammed but I assume that the site offers reasonable escrow service.
Read seller's rules/site escrow and make sure to check feedback/trust about sellers before purchasing any service.
If you are interested in gifts cards, this site
[3] offers a good alternative, buy a good VPN
[4] to prevent IP leaking.
[1]
https://bitify.com[2]
https://bitify.com/tag/netflix-trial-vcc/[3]
https://www.coinsbee.com/en/Netflix-bitcoin[4]
https://www.reddit.com/r/NetflixViaVPN/wiki/index