I have scavenged stepper (and DC ) motors from many printers. To open them you usually have to unscrew a few screvs here and there, and then pry some plastic tabs apart.
If the printer has a built in powwr supply it's a good idea to keep it to power the motors.
Also save some of the other mechanical parts like the steel rods the printhead is moving on it might come in handy in your project.
In inkjet printers there are usually one stepper to advance the paper and one DC motor that moves the printhead, sometimes they are both stepers. But they are not the highest resolution steppers.
The best steppers i have found came from old scanners, and very old 5.25" floppy drives.
If you can get your hands on some the old big Apple Imagewriters you should take them, they have really big and good steppers.