If you are using WooCommerce, you can assign a product of your catalog to an item, from the item view.
Information of the item will be filled automatically, and you can change the title and the picture if you want.
From the form settings, you can enable the option to add selected products to cart or not.
If you activate this option, only woo products can have prices in the form (other items can be used for conditions and information), because the woo cart will use directly the price defined from WooCommerce.