Conditional Product Displays

Can I display products in a payment box based on conditions?

Unfortunately, this is only possible with regular fields, I'm afraid that it's not possible to show/hide products. 

An alternative would be to use regular fields for your products so you can handle them with conditions, you will need to manually perform the calculations and pass this to the payment field, here are some guides that will help you with this: 

https://www.jotform.com/help/301-How-to-Assign-Calculation-Value

https://www.jotform.com/help/275-How-to-Pass-a-Calculation-to-a-Payment-Field

https://www.jotform.com/help/259-How-to-Perform-Form-Calculation-Using-a-Widget

I hope this helps.