In most cases, when a product is on sale, WooCommerce displays the (crossed-out) regular price alongside the price on sale. This is a great way for customers to see how much they’re saving on a product.
One of my pet peeves about WooCommerce is that, when it displays a price range (which can happen in variable and grouped products), it only shows the final (on sale) price.

I get the reason behind it. Showing two price ranges one alongside another results in a very long, aesthetically-unappealing price tag.
But for me, there are other options that are preferable to hiding the regular price altogether (such as tweaking the result with CSS).
If you, like me, would like to modify WooCommerce’s default behavior to display the regular price anyway, keep reading. You can also find the final result on Github.