I know, video shooting with on-the-fly autofocus on a low-end DSLR doesn't exactly set your ass on fire. Regardless, here it is, available on the Nikon D3100 and it only costs $700.
That's right, no more using manual aids to keep a subject in continuous focus while shooting videos on your DSLR. This one does it all on its own, all while grabbing full HD 1080p captures at 24 fps (and 720p at 30 fps). It uses Nikon's Expeed 2 technology for the purpose, which constantly adjusts the optics to keep the intended target as the main attraction.
The Nikon D3100 sports a 14.2 Megapixel DX-format CMOS image sensor, 11-point autofocus system, ISO up to 12,800, a 3-inch LCD, built-in pop flash and the usual DSLR features. Aimed at entry-level users, it comes with a Guide Mode, which offers mini-tutorials that you can watch on the onboard screen for getting the most out of your shots.
It comes with an HDMI port for plugging into an HDTV and can respond to most TV remotes (so you can control images and movies while staying on the couch). Compact and light, it measures 4.9 x 3.8 x 2.9 inches and weighs approximately 16oz (body only).
Now that the Nikon D3100 has the continuous autofocus videocam mode going, you can expect the others to catch up pretty quickly. Still, this one sounds like a decent machine at a rather affordable price. You can catch the rest of the specs from the link to the product website below.
Nikon D3100 14.2MP Digital SLR Camera with 18-55mm f/3.5-5.6 VR & 55-200mm f/4-5.6G IF-ED AF-S DX VR Nikkor Zoom Lenses
Sale Price: $599.99
Nikon D3100 14.2MP Digital SLR Double-Zoom Lens Kit with 18-55mm DX Zoom Lenses (Black) (OLD MODEL)
Sale Price: $190.36