Went looking for batteries for my new spark. Target has them on clearance for $24.98. I was able to price match between Targets. Use a red card for 5% off and the current coupon in the app for another 5% off, for a total of 10% off on top of these prices. Thanks to starfox54 for confirming that. They show full price online, but ring up at the clearance price in store. There have been mixed results with price matching. Some locations have them in the electronics clearance section, some still have them in the case with the drones (usually by GoPro stuff).
The DJI Mavic Intelligent Flight Battery (8138068) is $45 (50%) in some stores as well. Thanks to Formless for the mavic info. Note, these are for the Mavic Pro, not Air.
Update 10/14/19 - Not sure when it happened, but the price was lowered again. BS is now showing them at $14.98 for Spark, $26.98 for Mavic Pro. Huge YMMV as I'm sure they are mostly OOS.