ezo is a minimum of board and carrier board which is atleast $55. With the pre-built ones you support a follow member and don't have to deal with the ezo crapping out on you after a few months.
Not entirely correct, you don't need the carrier board to hook up the EZO, however it makes it easier. I looked at a pre-buit but I couldn't find any in stock. Anyone have any or know of any in stock?