Fair price for a non-gray market d90 with 18-200 lens?

What type of lens is it? If it is the Nikkor lens with VR then the lens alone is in the 700-775+ dollar range. If it is a Tamron lens then they go for about $300. I have purchased several Nikon mount lenses in the last year from online retailers and from Wolf camera.

Third party lenses cost significantly less than Nikon lenses. The question you need to ask yourself is this... do you need/want the exceptionally high quality glass that Nikon is selling.

If you plan on going budget on your lenses then go to the store and check the quality, even if you plan on buying online. Not that the third party glass is bad (the reverse is the case) it is just that Nikkor glass is really that much better. Keep in mind a good quality lens will last you a lifetime and you can buy functioning lenses on Ebay from the 1950s.

If you are trying to compare prices of the D90 to an advanced digital- keep this in mind.... most superzooms marry small sensors + outrageous MP (There are a few notable exceptions like the Fuji s100fs, Lumux Fz50, which use larger sensors). The camera makers add the high MP count as this is what their target audience (for most of these cameras) has been judging cameras quality by. Small sensor + very high MP is a shotgun marriage that needs to go away-- the new trend is larger sensors and more reasonable zoom range which is a very good sign/direction.

A SLR has better quality and larger sensors.

The other thing their target market is looking at is zoom ratio- once you exceed the 400 mm equivalent shake becomes a huge problem- exceeding the 500 mm equivalent will most likely produce shake (produced by blood flow of the human body) even if stabilized unless it is on a tripod. The greater the range of lens/cheaper made it is will produce aberrations.

The Tamron glass is going to be as good if not better than many of the lenses of the sub 400 advanced cameras. This trend is also reversing with camera makers... they are using better glass now days. The advantage of the SLR is you can purchase the cheaper glass or a lens with slightly less range and upgrade. I personally would recommend, as a starter kit; a Quality Prime Lens (Fixed length), a good quality super telephoto 70-300 mm or 55-200 mm, and a Macro lens (Or at least the kit lens + close up filter).

Anyhow to answer your question fully, the Nikon layout you described would run you (As of this writing) 1100-1900+ depending on what lens you go with (Sigma and/or Tamron lenses on the cheaper side), and would be a relatively high quality camera system.

If you are asking because you think you are about to get an amazing deal from an online retailer- check out their reputation. A certain online company is known for bait and switching, not delivering goods, and trying to Up Sell you into a 50-100 dollar media card ( A 8 Gb card should cost around $20 or less now days for most brands) or a battery pack that is marked up 300X its value. What I am telling you is stick to trusted dealers like Amazon, Adorama, WalMart.com, RadioShack.com, Beach Camera, Office Depot.com, Dell.com, OfficeMax.com, Frys electronics.com, TigerDirect.com, Target.com, Sears.com, Willoughbys.com, HP.com, ... always check out the retailer and if the deal seems to good to be true it probably is.