Turn your Shopify store into a multi-vendor marketplace like Amazon or Etsy. Allow various sellers to create accounts, add products, manage inventory of their products, and view orders of their products. Take a commission on sales or charge a monthly fee. Integration is seamless to customers.
I have set up 3 marketplaces using the Webkul Multi-Vendor Marketplace app and am familiar with optimizing it, its ins and outs.
This base fee assumes that your Shopify store is already created, and you just need the marketplace conversion taken care of. If you do not yet have a Shopify store created, select the "Ground up" add-on to include base Shopify setup as well.