Student Camera Options
For a school program you will want to get new cameras. For personal use, used cameras are fine, particularly if you do not mind having to fiddle with them or send them in for repairs. But in your situation I strongly recommend that you go with new manual cameras like the Vivitar V3800N or the Nikon FM-10. You will not have time in the middle of a semester to wait for a new camera to come in, or to repair one. I believe that both cameras are being produced by Cosina and sold under their respective brands.
Neither camera will be as stout and reliable as the old standbys that many of us remember, so you will be faced with an occasional broken camera. Because of the low price they should probably be treated as throw aways because a repair, if even possible, will likely cost as much as a new camera. In your situation I would call BH Photo, Adorama or Freestyle and see if you can set up a bulk buy with a store warranty where you can return non functioning cameras to the store for credit against new, replacement cameras. Vivitar or Nikon may provide warranties but, if so, I suspect that the warranties are not intended for school photography programs so probably will not be of much help for you.
I am partial to the Vivitar V3800N as I use the Pentax K-Mount lens but I seriously doubt that there is a lot of difference between the Vivitar and the Nikon with the exception of lenses, and a slightly higher price for the Nikon. I have been successfully using the Vivitar V3800N for my own personal work for over two years now and the camera has been very reliable for me. In the past two years I have shot over 100 rolls of Kodak BW400CN and Kodak Tri-X in the Vivitar and haven't experienced a single malfunction. I have been quite happy with the performance. I do not purposely abuse it but I use it while hiking and traveling off-road so it does not lead a pampered life. However, please be aware that I have used this camera fully expecting that I will replace it if something major fails, not repair it.