i would aggree with ian on this. as a responsable breeder you either have to know you have homes lined up for these bucks, have room (and want to) keep them all yourself, or cull them. why not think about sexing at day 1 and taking the bucks out before they look like mice, at this age you can pop them in the freezer (i wouldnt do it over day 2) otherwise you need to sort out a chamber, or a method of culling. - do you know anyone with reptiles? you could always try finding a feeder breeder in your area who can do the culling for you and then can feed the mice (as long as they arent live feeding)
otherwise, like ian said perhaps you ought to limit the amount you breed and how often, as imagine if sods law would have it that the next load of litters you have have got 14 bucks in each! Big problem!
It is sad, and its never nice to cull an animal but you have to decide why your doing it and if its worth it. I would say dont let them get bigger than you need to. if you take them at a couple of days or wait till the markings come thru if u need a good marked buck then take em out - u will also notice a difference in the other babies size as bucks tend to be greedy sods.
failing all that, save a load up, any age taken and drive to the south east and i'll take em off your hands for food (snakes not me)