Yangdock E-commerce via Amazon offers the Masione 20-volt Lithium-Ion Rechargeable Replacement Battery Pack for Black + Decker Tools model no. LBXR20, for $18.99. Coupon code "MASIONBD" cuts it to $15.19. Plus, Prime members bag free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $5.67.) That's $3 under our mention from July, $18 off, and the best price we've seen. It's compatible with a variety of Black + Decker models; check the product page for more information. Deal ends March 17.
Note: It's backordered until March 17, but can still be purchased now at the above price for delivery when available.