Prices and ablity vary. It all depends on what you want to do with it. Which device do you want to get footage from (camcorder, TV, etc.)? Do you want a capture card or a USB capture device? Do you want to burn the video to a DVD or CD-ROM? How much are you willing to spend? And of course, you'll need video editing software. Do you want that included? Or do you want to spend more on another program?
Those are just a few things to think about. Maybe a more experienced person can help you out more. I not an expert, but here is a good resource to help you make some decisions:Video Help.com
This site has everything you need to know about video and video capture (and then some!). I have researched this topic a little, because one day, I want a capture device for my computer (lack of cash prevent that now!).