Yes it seems CbB is not for those who do not have good internet at home. I used to be on a Cell Phone Smart hub. It only had 3 GB per month. I did all my downloading at other peoples houses.
But I wonder? what happens if you download and save the installers, transfer to a new computer and hook that up to its limited connection. That would at least save the bandwidth.
But if you have no internet your only choice is to take that machine to a place were there is.