I love learning stores for educational toys/games/art supplies for the kids and this one does not disappoint. They have a large selection and the staff is friendly. Some items may be considered overpriced, like another yelper suggested they could just go to Wal-Mart for their pens, but that's expected.
I, myself, am not a teacher but was shopping with a girlfriend who is. She shared the same sentiments about there not being much for a teacher who teaches outside of Elementary. Nonetheless, it's worth checking out. I also believe they offer a teacher's discount.