For me, security of the site is the most important aspect. In the time I was playing NBA 2K21 before, I bought NBA 2K MT from several sellers and the number was quite huge. If the amount of an order reaches some amount the verification process is initiated. This could be an issue. I have to submit photographs that are related to privacy for verification. Following that I am extremely concerned about the possibility that my personal data will be sold to these sellers.
Another important aspect is the security of the funds. There are a lot of scam websites that profit of the players' habit of paying attention to the price of products and also sell low-cost products on their website, however they don't ship the goods until the buyer has paid. Many players who purchase game-related services from the website who have experienced this I believe it's quite remarkable.
The trustworthy seller I suggest is NBA2king and their customer service has always made me feel satisfied. In regards to delivery speed or customer support, NBA2king has not disappointed me. One of the most important things is that the site is extremely secure and allows the most secure payment methods since NBA2king is a partner with their customers. I'll buy another 2K22 MT at NBA2king!