How can I create a product with a customizable sales price?

I'm selling products, but also taking donations to a non-profit organization. It appears as though I am unable to do both in the same form, so I was trying to create a product with a customizable sale price, but do not know how. Right now I've created two fixed donation prices, but would like to have the option for the customer to enter their own price. 

I would suggest putting a 1 dollar price then enable the custom quantity property. You can then hide the price in that item using a custom CSS codes. Quantity x price (1 usd) = total donation.

https://www.jotform.com/help/225-How-To-Add-Options-In-The-Payment-Form

Let us know the form after so we can help you get the right CSS codes to hide the price.

Here's an example form: https://form.jotform.com/60304952877967