They also have disposable desks and bookcases.

Look for furniture that will withstand someone leaning or sitting on it. The cheap designs are held together with cam-lock nuts and bolts or screws, and it's inevitable that at some point someone will lean on the desk and pull the screws through the particle board.

Furniture that will last longer has multiple fixings to keep it square, or diagonal cross-pieces (or a flat sheet).

This is going to last much longer:

    ..._____________
    ..._______•__•_|   
       \\   |      |
        \\  |      |
         \\ |      |
          \\|      |
           \|      |
            |      |

Than this:

     ..._____________
     ..._________•__|   
             |      |
             |      |
             |      |
             |      |
             |      |
             |      |