On any of our paid plans, you can customize the launcher button for your Wishlist module to an icon of your choice. You could either choose one of the available options (heart, star or a thumbs-up icon), or configure a custom icon of your choice. If you are choosing the custom icon option, your icon file should be a png or gif file of size 40px X 40px. 
You can configure your launcher icon via the Dashboard > Setting> General Settings screen, as shown in the image below: 

 

Make sure to save your settings after making any changes by clicking on the Save button the top right corner, and clear the browser cache and cookies to see your changes on the live site.