If you find it expensive to purchase the “official” Swiffer Wetjet cleaning solution, you can make your own or purchase more economical floor cleaning solution and refill the bottles.
There are two ways to remove the caps on the end that prevent you from refilling it easily (because they don’t want everyone to stop buying their cleaning solution!) First, you can run the top of the bottle under hot water then pop the lid off. Or you can use pliers to unscrew it, since pliers grib much better than your hands!
Refill it with cleaning solution, insert back into Swiffer Wetjet, and start cleaning.