For starters, use what you already have access to; your phone, your digital camera.  These days with the popularity of sites like Youtube, Vimeo and Vine, we are used to seeing lower quality pictures.  So long as the audio quality is good and you plan well, the camera is less important.

Once you get into the swing of things you might want to upgrade. (You don’t have to!) There’s a good tutorial and video here on choosing a device that’s right for you.