Visa agencies charge money for their services so going yourself is always the cheapest option. However, a good visa agency (not all are good – please check with your student advisor regarding recent recommendations from other LTL students) not only saves you time and the need to queue at the embassy yourself – they also check your visa application before it is handed in and can inform you about any current specific requirements the embassy might have. As it is usually the little details that are not properly published on the internet, like a wrongly filled out form or applying at the wrong embassy, that lead to problems and delays, applying via an experienced and reliable Chinese visa agency might end up saving you not only time, but also hassle.