Barnes & Noble has announced a new promo for those who are buying Nook devices, currently in effect and running until March 18. You can purchase the Nook Color or Nook Simple Touch at a $20 discount if you use your MasterCard to pay. The deal is valid at the almost 700 Barnes & Noble stores as well as at BN.com. So this means that if you’re planning to get the Nook Color, you’ll only be paying $149 instead of its usual SRP of $169. If you want a simpler e-reader, you might want to consider getting the Nook Simple Touch instead. You can grab one for only $79 instead of the usual SRP of $99. Just to reiterate, this deal is good until March 18 only. So, you still have two days to decide whether you’ll get the Nook Color or Nook Simple Touch.