There are two ways customers can make a selection in a product builder, choices or options.
With options you can't change the price, you have to use choices to do that.
For example, if you'd like to charge $10 for custom embroidery, make a step "Do you need custom embroidery?" and then the two choices would be Yes and No. Yes, would be associated with a product in your store called "Custom Embroidery Charge" with a $10 cost.
On the next page where they enter the options, the field text etc there's no cost adjustment needed. You can use the conditional logic to show or hide that step based on whether they select Yes or No to the custom embroidery.
For detailed instructions, visit these pages: