I think you're being amazing giving him any money at all!
I started uni in 2003. My balance sheet (yes I had a budget spreadsheet to help me manage my money) looked something like this:
Income (per academic year): £7500
Outgoings (per academic year): £7400
My income was made up of:
Student Loan £3000
Summer Hols Earnings £1500
Weekend Job Earnings £1600
Student Overdraft £1500
Total: £7500
I think it was one of the most worthwhile lessons my parents taught me. I hated them at the time, and was uber-jealous of my student friends who had Asda food shopping delivered like a parachuted food parcel every two weeks and money put in their account every month.
But having gone through 4 years of extreme budgeting I now know how to balance my bank account and save up for things I want. I still use the weekly budget spreadsheet my dad set up for me now.
I had three jobs in the summer hols before I started uni (saturday job in shop, bar work 3pm-midnight, factory work 6-12noon) to give myself a cash start for the uni life. I worked my butt off, felt really proud of myself and really learned the value of money and then turned up at uni to share a flat with students whose parents sent food shopping every fortnight, gave them a monthly allowance and still paid their mobile phone bills.
It is of course completely dependant upon how good your child will be with cash - my parents knew I had some sort of level head on my shoulders but my brother is the polar opposite and is now living back at parents to save cash.
I think what I'm saying is, if you are in the position to make your kid's uni life comfortable, great, but if not, encourage them to get some of their own cash behind them. Trust me, they won't waste it all down the students union 3 nights a week (and might only go once a week instead)