Attribute options for multi-value product attributes can be configured as price and weight modifier options that will increase or decrease the product's price and weight (the product's weight affects the shipping cost).
Here's an example of a price modifier option that allows customers purchasing a denim jacket to add embroidery for an additional $10 per unit:
Here's what it looks like on the storefront:
If the check box "Add embroidery? (+ $10.00)" is selected, the product price changes respectively:
To configure attribute options as price/weight modifiers:
Hover your cursor over the field displaying the attribute option to that you want to add a price and weight modifier. A link titled "Modifiers" is revealed.
Click on the "Modifiers" link. It displays a popup panel allowing you to specify the price and weight modifier; this option will be altered if chosen.
Use the "Price" and "Weight" field(s) on the popup panel to specify the modifier values you require.
If editing product-class or global attributes, choose to apply the changes locally or globally.
Click "Save changes." The settings will be saved.