Black & Decker LD120CBFR 20V MAX Cordless Lithium-Ion 3/8 in. Drill Driver for $15 in my store. (YMMV) This drill comes with one 20V 1.5 Ah battery (LBXR20) and claims it holds a charge for 18 months.
Previously FP deal at $21. Not the best drill, but battery is worth the price alone.
I am including the BrickSeek link, as this is YMMV. Some locations as low as $10, some still at $21. Pick up in store available.