D200+18-200VR owner here
A few questions...
Is this your first DSLR?
Have you played with a D200 in a shop yet?
Are you easily intimidated by lots of controls?
Do you intend to post-process?
To expand on these comments...
The D200 is a complex beast. If you need to be able to rapidly change ISO, shooting mode,focus mode, metering, white balance etc, and be able to check the setting by glancing at a switch rather then digging through menus, the D200 is for you. You DON'T get AUTO, or scene modes. The camera is built like a tank, and weighs a ton (well a kilogram actually!) It's also the biggest DSLR on the market until you get up to the Canon/Nikon pro models.
The D200 also has very conservative metering, and very bland jpg conversion. In other words, it cries out for RAW shooting, and taking them into Capture NX (free with the D200 now I believe).
As Paul says, if this is your first DSLR, you might be better off with D80 or even a D40. The D40 has a shallower learning curve if you're scared by lots of buttons and jargon. The D80 has 90% of the D200 features, but at a very keen price. The main things the D200 has over the D80 are weather sealing, 5 frames/second (and bigger buffer), ISO displayed in the viewfinder, and mirror lockup. If you'll use these features rarely or never - save yourself some cash!
If you shoot sports, or do a lot of tripod work, the speed and lockup mode will be very useful though.
Getting back to your original questions though:
You're unlikely to find an 18-200VR at a keen price in a shop. I'd suggest getting the body from a bricks & mortar store, and shopping around for the lens. I got mine from Photooptix, and the 18-200VR mail order from a store in Cheshire after MUCH hunting.
Accessories:
Sandisk Extreme III (at least 4Gb if you shoot RAW+jpg- I have a 2Gb and an 8Gb)
Spare battery
STURDY tripod. The D200 will cause cheap tripods to shake all over the place. I have a Uniloc 1600 Major System+Manfrotto 410 geared head (superb for macro work, but not so hot for rapid adjustment)
A D200+18-200VR will just fit into a one of the Lowepro topload zoom 1. It'll also go in a Lowepro Slingshot 200. My usual 2 lens bag is a Tamrac Explorer 2, which will take the D200+18-200VR with hood reversed, and another large lens with hood. For protection, I use the Hoya HMC Pro1 UV filter.
Rocket blower
The other thing I'd recommend is a fast prime lens if you intend to shoot moving subjects in low natural light. The super cheap and tiny Nikon 50mm f1.8 is almost a no brainer, though the Sigma 30 f1.4 or Nikon 35 f2 are more versatile.