Just a heads up. I noticed earlier today B&H has the Konica Minolta NP-400 batteries back in stock and still $9.95.
These are not off-brands, they are OEM Konica Minolta. I've been using them interchangeably with the OEM D-Li50's and noticed zero difference in charge life.
Get 'em while they got 'em!
Konica Minolta | NP-400 Lithium-Ion Battery | 8699X001 | B&H