Anyone know if this coupon is still accepted and if competitors are still accepting it (the latter probably not)
I can't imagine any competitor paying one ounce of attention will allow the coupon.
As for Staples, my understanding is that their computers are set by default to accept their own coupons up to X days after expiration. Knowing this in advance was the only reason why I was willing to try mine on the day after expiration (although I did have a backup plan as well). Unfortunately now though, I don't know for sure what the value of X is. I want to say I seem to remember it was four days after, but I'm really not sure.