First a disclaimor: we shot this video for Sanyo. However, we (Bikeskills) did not receive any compensation for it, the goal being to get some exposure for our various cycling and action sports programs.
All we really want to get across here is for you to see what we captured with Sanyo's low-cost ($299 - $599) Xacti Dual Cams. We have no idea if there are similar, or even better, cameras out there at that price range, with the HD video / still combo capabilties: we typically use Panasonic P2s for bike work, film camera for skiing, and various setups for our surfing work.
The bottom line is that we were, and are, impressed with how the bike video turned out. In particular, the image quality was what we wanted, and the 240 frames/sec slo-mo was more than we expected (although 600 frames/sec was not good enough for our purposes) and the stills were also more than what we needed for web/TV and the still/sequence shot capability was real handy.
Are the Xactis or cams like them good enough for real-deal pro use? Hard to say, but, if you are looking to spend less than even a couple of thousand dollars for video and still cameras, I think the Xactis are a good place to start. Again, there might be several firms making this type of product; the Sanyos are the only ones we know about, and actually used. Here's the video link: