Edited December 9, 2019
at 03:45 PM
Amazon.com has the Dewalt 20V MAX XR 5.0Ah lithium-ion battery two-pack for $124.99, less a $25 discount at checkout, for $99.99 (plus tax), with free shipping. Ships from and sold by Amazon.
It is currently out of stock, but expected back in stock on December
14. Order now, and Amazon will ship when it arrives.
QA Edit: Amazon deal expired, no more in cart discount so $124.99. But see front page post for another option via eBay for the $99.99 price.