Rowing is one of those exercises that not only looks difficult but is difficult. The upshot is that it's one of the best exercises you can do. Not only does it work your legs, but it also works your arms, core, and pretty much every part of your body similar to swimming.
Of course, going out and rowing can be a bit of an endeavor, which is why rowing machines are handy. Thankfully, Amazon has a sale on the great Circuit Fitness Deluxe for just $199.57, which is a whopping 54% discount from its original $432.87 list price.