What can be done with dozens of used printers ?

Obviously, they can’t be thrown in the garbage; and since they’re still perfectly good machines, recycling might not be the best option.
Donating to non-profit organizations is one possibility.
Are there any businesses out there that would pickup the machines and/or purchase them?

These machines vary in age from old HP printers with parallel connections to recently purchased Dell multifunction machines. Inkjets range from photoquality multifunctions to much older parallel connections. There could be as many as 50+ devices. All are fully functional and currently in use. I’m located in Central Texas.