I got my 6.5 for about $80 at HF, you'll also need a clutch that will be around $30, and unless you are comfortable installing the motor you should consider the mounting kit sold here which will be more (search it and you'll get the price for that). I haven't read any negative responses to the kit, it has been highly recomended by people that could probably do it easily themselves. Over all, I'd probably just get the 6.5.