An online store is a different job from a brochure site. It has products, stock, shipping, taxes, payments and the emails customers get after they buy, and every one of them has to work every day. Most stores in the region run on Shopify or WooCommerce (a store added to WordPress). Larger or unusual ones run on custom platforms.
This page lists the Southwest Michigan firms that say they build online stores. They range from a veteran-owned company in Three Rivers and a founder-led studio in Holland to a Battle Creek development company and a Kalamazoo firm that take on custom platforms and integrations. If your store has to connect to an inventory, accounting or point-of-sale system, say so in the first conversation. It changes who can do the job and what it costs.