This might at first seem like a great idea...hey I don't need to write my own paper, AWESOME
BUT...
Most Universities now use some of plagiarism detection service, and they are very accurate in finding whole essay papers, and even portions of papers not cited correctly(generally a sentence or paragraph that is not cited correctly can be considered plagiarism).
Universities have various different policies on enforcement against plagiarism, maybe a notation on your record or possibly even being expelled.
So think carefully before you decide to pay for your essay paper, it could haunt you for life.