In reply to MikeTS:
You're welcome.
I thought I'd said something wrong. That's the problem with a text only environment, confusion builds up.
If you are a Nikon fanboy then Nikon lenses are great for their cameras.
However with my limited pocket money and a beady-eyed better half, then I have to be careful what toys I buy with what I think I can get away with before I end up on the wrong end of a thick ear.
This means, for me, at the budget end of camera lenses then Third Party manufacturers have to go the extra mile in quality and workmanship to compete with the perception built up around a brand name. And, Nikon is a reputable and big brand name.
Perception almost always exceeds the quality of goods on offer at the lower price point.
From my own personal experience of buying budget Nikon lenses and Third Party lenses like sigma, then I have always been extremely happy with my Sigma purchases. I have not been so content with my budget Nikon lenses. That is not to say that Nikon's premium lenses are the same, its just that they are out of my price range.