The Mann Co. Store is an in-game micropayment service included in the Mann-Conomy Update. Mannco.store is a great alternative for Steam Community Market (SCM). Not only is it cheaper to buy from, but you also get more from your sales. Yes, we believe ManncoStore is legitimate. Here’s a quick summary: Mannco.store receives more than 350,000 visitors each month, according to SimilarWeb data.