Shopify App Development

I would like an app creating for my university. On my products, instead of having a normal price, I would like it to have a box that accepts manually entered amounts, so that students can choose how much they want to pay. I will use this to accept tuition fees. Tuition fees vary from student to student, so we cannot have a fixed amount.

Here is an example of how I would like it (also see screenshot):
https://pay-what-you-want-demo.myshopify.com/products/15mm-combo-wrench?variant=35591980843158

Although this app is very slow, I would like a better one.

Thank you, I look forward to working with you.