I have the opportunity to buy items and immediately sell to a company at cost, how do I not get my cards shut down from maxing out my cards buying items and selling them?

IF THIS IS AGAINST THE RULES MY APOLOGIES IM NEW. Also for the record I am not HERE to promote anything. So I'm apart of a reselling group and I noticed they have a buyback group where they will buy items from you for either MSRP, a couple cents over MSRP, a dollar or 2 over or for a couple things like commemorative coins, $40+). It's obvious for credit churning. It got me thinking I could just spend all the money off each card and get the money back in less than 2 weeks but I don't want them to close my cards because of this. What is the smart way to handle this?