The short answer
There is no single college-cost figure. The answer changes most with accommodation, travel and the supports available. Build the budget in categories, separate once-off setup costs from monthly living costs and check official student supports before deciding what the family must fund.
The headline fee is rarely the whole cost. Accommodation can dominate one student's budget while another lives at home but spends heavily on transport and time.
Build the real number
Give the student a weekly amount and make the larger term costs visible. A budget works better when both sides know which costs the family is covering and which the student is expected to manage.