Hi,
these things are always personal taste and no one size fits all. That said I have a Logitech Quickcam Pro 9000 that works very well with Skype on my Thinkpad T43. It's a couple of years old now, so there may or may not be an updated model. When I bought it, it was around £40 UK - I won't do the conversion, computer hardware is a lot more expensive in the UK than the exchange rate would suggest! Anyway, for what it's worth, this is what it says on the side of the box:

Carl Zeiss Optics (i.e. a decent lens)
Autofocus Lens (Hint, turn off the face following feature unless you plan to sit very still!)
High Definition Video - Capture up to 1600 x 1200 (But bear in mind the bandwidth on your internet connection)
Up to 8 Megapixel Photos (interpolated from native 2 MP sensor)
Microphone with Rightsound(tm) Technology (works very well for me up to about 3 or 4 feet but then I have a fairly quiet house)
Up to 30 frames per second Video
High speed USB2
Logitech Quickcam Software (Not the most user friendly interface but works well)
Universal clip (Attaches to pretty much anything but best with laptops and flat panels)
Works with Skype, Windows Live Messenger (built in to the Logitch menu) and other instant messaging applications
2Year Manufacturers guarantee and service

That may be what you are looking for or could be a benchmark to look for a better deal. It works for me but as they say, your mileage may vary!