If you want a decent type, like example 1.3 Mega pixel type,
prepare yourself around 60-80 bucks.
If you just want normal normal type, seldom face people, get a VGA
type, prepare yourself around 15-40 bucks. (Note, the cheaper it
is, the more blur effect you will receive. Some frame rate might be
slower and result look pretty laggy).
All webcam work on both desktop and laptop, no specific type (those
I have seen).
Side note: don't flame me if I gave you the
wrong info. I got my webcam last year. You can try your luck in
upcoming SITEX event.