By default, the bundle price is not displayed as a sale price (i.e. not displayed alongside with a compare at price).
Merchants may choose to set a sale price for the bundle.
To do this: first override the bundle price (optional), and then check the Display as sale price? option.
Click on Create Bundle or Update Bundle to finalize this change.
Once checked, customers would be able to see the overridden bundle price as the sale price and the original bundle price as the compare at price.