Is there a substitute for a webcam, like using my digital camera or camcorder?

if not, whats the best quality and affordable webcam out there ($20-$30)?

Some cameras can, I have an Olympus c2100 and it has that option, if you have the software for them, but if you don't have a power supply they will go thru your batteries real fast. But a webcam is propably cheaper.

40 $ at walmart a webcam , you can use digi cam but will use up a lot of batteries

Most digital cameras and video cameras will not work as a make-shift webcam (they don't support that ability). If you go to ebay, you can get a fairly decent webcam for about 20~30$ Or, check out craigslist. Some people bought webcams and decided they didn't need it. Great place to buy working webcams for really cheap.

Any cam with video-output can be hooked up to via USB with a device like the one I have, called an EZMaker USB 2.0 by AverMedia. Most digital cams can be USB'd and work as a webcam without additional hardware.