There's quite a few out there, just wondering if anyone has tried one? Here's one: Amazon.com: CTA Replacement Battery for Sony NP-F960 NP-F970 NP-F975: Camera & Photo

Good bit less expensive than Sony batteries, just wondering....

They work no problem in my experience, Have used a variety of "cheapo" batteries on MRC1 and camera with no probs. Only thing with the MRC1 - depending on where/if you have it mounted on camera, the unit is quite light so a smaller battery is sometimes preferable.

(I often use an MRC1 on the hotshoe of a Sony HVR-V1 and if I put an NP-F970 on it's very top/front heavy, with an NP-F550/570, no probs)