Not all visitors / customers are treated equally. Allow only verified customers to purchase a subset of products.
Everyone can see your products and their variants, however they do not have access to the price nor to the Add to Cart button until they get an OK from you. Once approved (works amazingly with our Multistep registration as auto-verification tool), customers will automatically gain access and ability to order your products. With this Shopify add on, you are indeed the Darth Vader of your store :)