Get price field value from gravity forms to use in php code?

I’m trying to integrate Paysera (payment platform) with Gravity Forms. I have Gravity Forms with product price field, I need to retrieve the price field value to use in Paysera API code. I have paysera API code in seperate php file. So basically this is what I need:

On gravity form load -> retrieve pricing field value -> on button press redirect to /paysera.php and pass $ pricing_field_value.

Is this possible? Thanks for any ideas.