I've been buying used older Apple laptops. The pros are the OS is not nearly as likely to get messed up. Those kids go everywhere and are downloading everything. On Windows computers they often get screwed up even with cleanup and viral programs.
Also I've had no problems with missing KB letters, broken keyboards and esp broken hinges. I've also had no problems with audio in and out breaking which is common on the non apple computers at least for me.
The cons are the higher price of about $100-200, less powerful since they're so old and if too old inability to run the newer OSs. However, it hasn't been a problem as most of them are on FB, email, chat, and homework. You can download OpenOffice.org which is free and has 'Excel' and 'Word' compatibility and function. You can add an ext HD to get more storage. They all love the ext HDs for sharing with friends.
If you need more speed yada then go with Windows as you get a lot of bang for the buck there. They just don't hold up as well.