DVI frame capture hardware

[penagate]

Guys,

I need something that will let me capture frames from a DVI video source (a headless computer, to be precise) and store them to disk or memory. I don't need to record or stream video, just get single frames in a bitmap (or non-lossy compressed) format. Sizes will be typical desktop screen resolutions. Disk/memory usage is not a concern.

Edit: I'd prefer a PCIe card, but a USB unit would do.

The ideal hardware seems to fall under the category of a "frame grabber", but these are outrageously expensive. On the other hand, HDMI video capture cards are cheap, but these seem to be intended for recording video and so I'm not sure I can get pixel-perfect frames out of them.

Any advice would be great.