Cocktail is not free. Use Onyx or MacJanitor instead. All three apps provide GUI front-ends to the same commandline BSD maintenance utilities. It makes no sense to pay for what you can get for free elsewhere. My personal preference is Onyx because it has more features than MacJanitor.
I bought Cocktail a year or more ago and it has always worked great. Support is top-notch and features are always added. I have no problem supporting well made Mac applications with responsive and enthusiastic developers.