Shoppers pay your normal price at checkout. As more people buy, the price falls for everyone, and earlier buyers get the difference back as store credit. Every buyer has a reason to share, because each new buyer lowers their own price.
No lost orders, only extra ones. A sale is never blocked or cancelled if a goal isn't reached.
Install Dropflock from the Shopify App Store. Questions: support@packsaddlesoftware.com