I agree with sticking with oem's.. I bought a Nikon D2H and thought I'd buy a generic off ebay and the thing wouldn't take a charge. Sent it back, they claimed it never made in through usps... lost $28 on the deal.. yeah, the Nikon battery is almost $100, but they work.
Also had bad luck on ebay just now.. I use mostly NP1 batteries for work with IDX nimh chemistry.. most of my cells are coming up on 4years old, so I was looking to try some lion replacements. Bought a np1 generic advertised as lion 3000ma... they sent nimh 2000ma.. worthless... they're asking for rma. I'll stick with IDX.
Also two years ago bought chinese 40nimh 2500ma AA cells. None of them hold a charge over 1500 after only 20 charge cycles. They all went into the trash... Now, I mostly use sanyo eneloop and powerex imedion AA cells with outstanding results... after over 60 charge cycles on almost 50 cells in use they all still read at or above rated capacity. Excellent results! So, I think you'll pay one way or the other, I'd rather have dependable power in the field.
YMMV
John