hey imran !
the seitz is an old but very good and reliable follow focus.the price seemsto be allright,but keep in mind that you will need at least one motor with gears as well.the seitz normally comes also with a special extension cable for the third channel if , for example the dop wants to pull iris himself.couldn´t see it at the picture. it would also important to find out what cables come with it.believe me,cables are EXPENSIVE.
trx to also check out with seitz company itself (i think they come from switzerland) if this price is okay for a used model.
i have worked with a seitz a couple of times and it allways worked really nicely and accurate.that´s all i can tell you about it.hope that helped.
all the best and good luck