This reminds me of my number one response when "friends" come to me with startup ideas.
Your company is another company's feature. As in, you are trying to build a business, on something that is an afterthought, tiny feature for an existing company to add.
Shopify has been around for a while—since before Amazon became the everything-retailer that they are now. It started out of frustration at the myriad annoyances in trying to get set up using osCommerce and other tools of that generation.