Personally, I think it makes sense to get the children to take a tuition free loan for 4 years, and decide whether you should pay down the debt with your own money, and work out a payment plan, or let your kid shoulder the burden him/herself.
Why? Because things keep changing, and the money you may have set aside may be used for other emergency purpose. Getting an interest free loan is 1 way to juggle the need for cashflow.