I just graduated a few months ago, so hopefully I'll be able to lend some unique insight. Full disclosure: I lived on campus all 4 years and never rented where I went to school though probably 95% of the upperclassmen rented locally.
My sibling attends a Californian university and rents a room in a duplex. I believe there are 7 people living in his unit (2 doubles and 1 triple room) and they're monthly rent is about $4,800. Assuming the same for the upstairs unit (also students) the landlord makes about $9,600 in initial income monthly. I'd have to look it up, but I don't think the place is worth more than say 800k. It's operated through a property management company that keeps close watch on the students. They have an annual lease and their deposit was roughly equal to 1 months rent. The PM guys come by randomly to make sure the outside of the place still looks ok.
In my experience, college rents tend to be higher than your average rent (depending on distance to school. If you have something within 15-20 minutes on foot you are golden). I've also only ever heard of annual leases where I went to school and my sibling says it is the same where he attends (opposite sides of the country, he's in CA and I went to college in NY). Many students try, unsuccessfully, to sub out their lease over the summer.
Expect damages, most students don't keep the place too clean, so account for that beforehand.
Don't wait too long to renew the lease. Many college annual leases seem to renew sometime over the summer and many students lock down a rental agreement in late fall, early spring. Developing a relationship with the students is key (mostly this just means leave them alone and let them do their own thing) because they will then suggest the place to their friend network when they move out/graduate.
If you're looking for an idea of the number of students that may be renting, data on student numbers / university housing should be available on the school website. Many universities only guarantee housing for 1-2 years and most of the student body has to rent for the second half of their school career as a result. If you can, walk onto campus and check out the number of bike racks vs parking spaces, this will give you an idea of the percentage of the student body that walks/ bikes vs drives and the areas they'd be stuck renting in as a result. Also see if the university has any free bus routes as students will also tend to live in those locations.
Advertising suggestion: student newspapers are a fairly popular source for finding housing
