Via B&H Photo
B&H Photo is selling the Canon EF 40mm f/2.8 STM Pancake for $129, these were $199 when they launched. If you haven't taken the plunge yet, you won't be disappointed. In case you missed it, you can read our review of the EF 40mm f/2.8 STM pancake here.
There are a couple of other deals on popular Canon lenses that are currently going on. Both deals have an instant rebate after checkout has begun as well as a mail-in rebate with Canon.