Buy a pair of hair clippers and cut your own hair and the hair of your boys. Ladies/girls are exempt from this tip. Unless you want to do the bald chick thing.
We have 8 sons. Clippers have saved us a small fortune over the years. Eventually the boys get older and start making some $$$ and decide to pay for haircuts themselves, but as long as we are footing the bill they get the momma mauling them.
I buzz my own hair off about every month or so. A set of clippers are around $20-$30 and seem to last forever. Even if they don't last forever, they pay for themselves after a few haircuts. Go checkout Amazon or head over to Walmart (at your own risk).
Trust me nothing can go wrong.