Reinventing the wheel is not always bad

Reinventing the wheel is usually undesirable.  However, when it comes to creating application icons, it may be an option better than reusing what is out there. 

Application icons that are as tiny as 32x32 pixels are usually, and should be simple. Some platforms have special requirements, and/or a set of the same icon (e.g. Android).  It is much easier to use a tool such as Microsoft Expression Design to create the icon than reusing one found online. It takes only a few minutes.

Reusing others' icons first have the potential copyright issue, then the wheels out there may not have the perfect fit your wagon.