Well, how small are you talking about? With the technology available today you can start with a crew of 1 (or 2), you and your video camera and move up from there. You would probably need at a minimum a camera operator/cinematographer and a sound person. And one thing about filmmaking is that time actually is money so how much it might cost you is going to depend on how long you need them. And the cost of hiring professionals is going to absolutely vary depending on where you live and the level of professionalism you want.