I used about 100-200 dollars a month last year. Parents got me a debit card the summer before I left for school, and I had a good amount there, but I never ended up spending over that in one month.
Mostly the expenses that I ended up incurring was a haircut once a month, going to the movies once a month, ordering in pizza or eating out one meal a week, snacking at the school store, some room stuff at the beginning of the year, and the Netflix membership.
You probably won’t need much more, and even that was pretty liberal spending on my part, so as long as you don’t impulse buy a load of things, you should be alright.