A few comments:
- monorails are usually the cheapest on the used market because they are more cumbersome to take out into the field, but on the other hand, monorails usually have a significant amount of movements available. Landscape photography will frequently use some movements, but are usually less extreme. Architecture is more likely to use more extreme movements.
- conversely, field folders are very popular today, moreso than monorails, for that reason nice field cameras are usually a bit more than most monorails. For some people "technical" cameras are a different category, but I see them mostly as similar to wood folders, but made of metal or carbon fibre. They may have had more flexibility than wood folder unce upon a time, but today the don't have that much of an advantage. You can find either with any movements, but usually not the same flexibility as monorails (but they fold up nice and small.
- there are some monorails that try to bridge the gap by having ways to fold won nice and small. The Technikardan is a good example (my favorite 4x5). But most of these are more expensive than a garden variety monorail.
- one big disadvantage with folders is the layout of most of them (not all through) is problematic for very wide angle lenses. First, some don't have easily interchangable bellows,so you cant throw on a bag bellows (bag bellows allow more flexibility of movements when the standards are very close together like when using a very wide lens.) The second problem is many folders' design focus by moving the front standard only. In mane cases this means that when you have a ultra wide 75mm or wider lens, you will get the bed of the camera in the shot unless you jump through some hoops.
I wouldn't look to find a camera and lens together. Figure out the camera you think is appropriate for your needs, then start looking for lenses separately. Fortunately good 4x5 lenses can be had reletively cheap (compared to 8x10 lenses at least) The standard lens many people start with is a 150mm ƒ5.6. You can find a passable one for $150-$200. If you want wide the most common is 90mm, and long is 210mm. However there are /lots/ of other sizes and the 90/150/210 might not be your ideal grouping.
Don't forget all the additional accesories you'll need--dark cloth, loupe, film holder, and if you develop yourself, you'll probably need different tanks, or tank inserts. When I jumped from 35mm to medium format, the transition was quick and seamless. When I went from medium format to 4x5, it took sometime of acquiring stuff before I was ready to take my first shot.