B&H has a nice one with a cammed 150mm Apo-Lanthar. Not sure what else is included. The lens and the fact that it's B&H could make it pricey.
There's a good discussion of the various Technika models at cameraquest.com.
The ability to use the rangefinder is, in my opinion, one of the main reasons to use a Technika as opposed to some other folding 4x5" camera. So if you're going to get a Tech IV, try to find one with one or more cammed lenses. With a Tech IV, lenses have to be cammed to the body, so the serial number of the lens should be on the top of each cam, and the serial number of the body should be on the bottom.
Cost will depend on condition, lenses, and other accessories like a Linhof shade and slip-in filters or a compendium shade, compartment case, rollfilm backs, etc., but you should be able to find a nice kit with at least one cammed lens in the $1000-2000 range. An Apo-Lanthar or Zeiss lenses can push up the price even higher.
Don't worry about whether it comes with filmholders or a Polaroid back. These items are not expensive, and you can find them easily elsewhere.
If there are rollfilm backs, Super-Rollex backs with the lever wind are much more desirable than the older Rollex backs with the knob wind. Older Rollex backs are prone to frame spacing problems with certain modern films, and it's a design issue, so it can't be repaired.