If you're in the U.S. and eyeing a new Lumia 640 or Lumia 640 XL, you may want to direct your attention to the Microsoft store. The online store is currently offering a free pair of Nokia headphones when you purchase a T-Mobile Lumia 640 or AT&T Lumia 640 XL.
It's unclear if this is a brand new offer, but it's worth checking out if you weren't already aware of it. Unfortunately, Microsoft doesn't specify which Nokia headphones you'll score with this deal, but it's likely to be either the Coloud Pop or Coloud Boom headphones that Microsoft is currently selling.
If you're interested, you can grab either device along with the free Nokia headphones for at the link below.
Thanks to Menachem for the tip!