first of all how in the world did syags comment make it through.
for the op- i just got married and was in one of the brisk-esque yeshovos. so heres the lowdown. a dira will cost between 130-175 a month,175 is a bit high. youll need to pay gichon, chashmal, bezeq, and maybe gas. figure another 75-100 dollars. ass spending money. this depends on which yeshiva hes in. ie if its brisk he gets all meals etc., youll have to figure it yourself. i did ok on 250 a month, but im very frugal. for bein hazmanim youll probably need to give more for food, trips, daled minim,etc. anything else?