I was shopping at Staples yesterday for some last minute back-to-school bargains and picked up some Bic retractable pens that were .50 each (6 per pack). The ad stated limit 2, so I grabbed two. However, the cashier told me that they qualified for the Bic buy 2, get 1 free promo in the ad too, so I could grab another pack and get it free! This worked great and I verified the freebie on my receipt. That meant 18 pens for $1. It also worked on the .50 mechanical pencils.
Your ad may vary - this deal worked for me at the Fredericksburg, VA location.
Also, I received a Staples email that listed more deals than were listed in the physical ad. These were treated like unadvertised specials. For instance, my email said I could get two Staples school glues for 5 cents each. This was nowhere in the regular ad, yet I did find shelf tags advertising this. Unfortunately, the email ad also had 3 really nice free after Easy Rebate items, which I was told I couldn't purchase since, "if it isn't in our ad, it won't print you the rebate at the register." If I have time, I may go back and try to pick up those items and see if the rebate receipt does print after all. I showed them my Smartphone so they could see the ad, but they said they would not price match unless I had printed it out.