I think I’ll buy them for my next round of replacements. Thanks for the recommendation!
$13.49 for 8, Prime ($1.68 each)
They seem to sell 2 different charger+battery combos:
$23.49 for 8 + charger, non-Prime
$22.99 for 8 + charger, Prime
(check other sellers)
$26.49 for 8 + charger, non-Prime