Our local elementary school has a "recycle me" box in the school's main lobby for ink cartridges.
All the proceeds go to the school. Super easy for me just to drive by, park in a visitor parking spot then run inside and drop them into the box....although I usually wait until I have 3 or 4 cartridges to drop off.
It might be worth a call to your local school district to see if/who is in the program.