Not sure what lenses you're buying!? VR/IS are noticably more expensive, drving up the cost of all long focal length primes and zooms
When I went shopping for my 55-200 Nikon there was about £20 difference between the new (VR) one and the old Non-VR model. Didn't take me long to think about it.
Basics? Try this:
what are shutter speed, aperture and ISO? © 2004 KenRockwell.com