Lots of Dropshippers want to sell their own products.
The problem is when you order from a manufacturer, there's a minimum order quantity which usually costs you 1000s of dollars.
You don't have that kind of money to test your product!
Idea: A simple shopify plugin where you can place your product for purchase without ordering inventory. When someone clicks "Add to Cart", you get a "Sorry, just went out of stock" message with a chance to give your email so you can be notified when it's back in stock.
Test this by driving traffic to 10s of products and see which one is a winner.
Order in bulk and PROFIT!