Is it possible to create an extra price field to add a "sale price" to a product? I would like to do the following:

You have a checkbox "use sale price" and a textfield to enter the sale price. When the checkbox is checked we need to display the original price (linethrough) and the sale price next to it.
The sale price needs to be used when adding the product to the cart.

You can add the checkbox and extra pricing field to your product content type. But how do you achieve the other things? Can it be done by only using product pricing rules? I'm new to Drupal Commerce so I'm struggling a bit with this :)

Anyone wants to share his thoughts on this? Thanks!