I'm Richard - CRO Expert of a Free Landing Page Builder for more than 90000 Shopify merchants, I would love to provide a solution to your question.
In its settings, you can choose the price for the extra options.
Especially, PageFly integrates with Zepto, you can not only build a beautiful, high-converting store with PageFly but also use these apps to customize your products.
Let me know if you have any further questions. Like my answer, if you find it helpful.
Richard - PageFly