How to get subtotal of custom price when editing an order in backend?

Hello Guys.

I want to custom custom price when add product to cart. I search on google and find some way to do that. I can custom price when add product to cart but when editing the order. I can’t get subtotal of custom price. Can you help me?

What exactly you want to do ?

Make a custom option of type area and with any name and on the product view page add the price on the custom option through jQuery, then you will get values in checkout and also in order page.