SellUp is the #1 Action upsell app for Shopify. This allows you to trigger an upsell on a products “Add to cart” button. The customer is then presented with up-to 3 Upsells based on your rules.
This makes SellUp one of the most powerful apps you can have for your Shopify store. It will also pay for itself, win win!
SellUp is Free which includes 1 upsell. SellUp Pro costs just $14.99 a month and allows you to create UNLIMITED upsells (think of the possibilities!). With the increase in conversions and sales from cross-sells & up-sells, it will more than likely pay for itself every month.