Yeah, it deponds on you. You can also buy a webcam with mic, i found this pc USB Webcam with Mic from sourcingmap, just costs $8.99. You can check the below link to have a look. Hope this helps!
I just checked amazon, anywhere from $5 to $100 (probably more). And most laptops will have a usb drive, so pretty much any of them should work on any laptop.
Depends on what kind you're looking for. I think it also depends on the laptop too.