You control the price of the options directly in PowerStore after adding in your options. On the top of your product insert or update page will be the options, select the one you want to adjust the price for and just update the price of the item. Now if a user chooses this item with the option you configured the price will what you entered for that option.
You should think of it like adding a new product but only for that option. This is way it is organized in the db. You can also update all options for a product at once by checking this checkbox on the update page.