Lightweight is my middle name. I work on two continents. My U.S. kit is designed to be carried long distances over rough terrain; My European kit gets backpacked around cities and bicycled around my home town of Vienna. I need and use a lot of camera movements in my work, especially front rise and shift in the cities. I need a full-featured lightweight camera and lightweight lenses that cover well enough to include things like church spires with the camera leveled and using front rise and a 90mm lens. Maybe my thoughts will help you put together a kit that suits you.
The lightest camera I have is a Horseman Woodman, weighing in at 3.2 lbs (1.45 kg). It is nice to carry, but is not the most precision camera I've used and the bellows have a tendency to pick up pinholes. It has the advantage of allowing Technika boards to be mounted upside-down, thereby positioning the off-center hole above center and giving you a bit more effective front rise; quite useful when shooting in cities. Otherwise, one has to point the camera up and tilt the standards back to level and parallel to get more effective front rise. Back tilt on the camera is strangely limited by the hardware, but is normally adequate.
My current favorite for city work is a Wista SW with a wide-angle bellows. The SW is a DX with interchangeable bellows. The wide-angle bellows is half pleated, half bag and is simply a joy to use when lots of front rise coupled with shift (or even combined with tilts/swings). I can use lenses up through 210mm with it (the long bellows goes up to 300mm). I can easily vignette my 90mm f/8 Super Angulon without straining anything. With a DX (which I also have), I would have to crimp the bellows to as much coverage. The downside of the SW is that it's rosewood and a bit heavier. And it's rarer. I got lucky finding mine with both sets of bellows. I guess my point is that if you plan to do a lot of architectural/cityscape work that requires a lot of movements, you'll likely want something that will offer you adequate movements with short lenses like a 90mm, so you may be willing to compromise weight a bit.
For backpacking/hiking in the States, I carry a Wista DX. When using lots of movements, I'll often have to crimp the bellows (as noted above), but the cherrywood DX is just under 4 lbs (1.8 kg) while my rosewood SW is about 4.5 lbs. Besides, my SW lives in Europe (with my Woodman) and my DXs live in the States. I use 90mm and 75mm lenses on recessed boards and a 300mm (Nikkor M) on a top-hat board with both the DX and SW. Advantage of the DX is that it folds up with a small lens attached
So much for lightweight cameras I own. Other cameras that I would look at if I were acquiring another would be the lightweight Shen Hao PTB, the Chamonix cameras (several interesting models), the Toyo CF45 (carbon fiber) and, of course, the Intrepid. This latter looks to be a great value; lots of capability for little cash, but I've never handled one. If there are no stability or positioning problems, it is certainly the cheapest camera new.
As for price: once you have some parameters of what you want in terms of weight and movements, you'll see that there are a number of models that would fit the bill (those I've mentioned and maybe more). Then, you need to keep checking the used market till you find the deal you want. A new Wista DX goes for upwards of $1,200, but I've picked up two used in good condition for less that half of that. My Woodman was only $400. There are a lot of vendors from Japan that list cameras on eBay and elsewhere for fairly high prices, but better deals turn up regularly; you just have to keep looking.
My opinion on tripods: A lightweight camera doesn't need a monster tripod. And, if you're carrying your kit a long way over rough terrain, a lightweight tripod is a blessing. I carry a Manfrotto 3205 tripod coupled with a 3025 3-way head (it has only knobs, no long handles) in the field. I have two of these set-ups, one in the States and one in Europe (so I don't have to carry my tripod on the plane so often). It straps easily on my lumbar pack and fits in a regular-size suitcase. I might carry a carbon-fiber tripod if I could afford one. I have heavier wooden tripods for heavier cameras, but use them only rarely. The 3205 is sturdy enough that I have no qualms about using a 300mm lens on my DX or SW with it. When the wind comes up, I hang something heavy on it; my film pouch, my camera bag or the nylon bucket (designed for backpackers to carry water in) I carry in my pack, filled with rocks or sand. That does the job just fine.
Lenses: There are lots of lightweight lenses. usually you trade maximum aperture and some coverage for lighter weight. A few of my favorites: Fujinon A series lenses in 180mm and 240mm focal lengths, the Nikkor M series 300mm (the 200mm would be nice, but is rare and expensive on the used market), the Fujinon C series in 300mm is also great. 210mm Plasmats, et al., are too big and heavy for me, I like the aforementioned Fuji A 180mm or the 203mm Ektar in this range. A 210mm G-Claron would be fine here as well. I've got a 210mm Fujinon L that is okay, but a bit large, if not as bulk as the Plasmats. However, the 135mm Plasmats are small enough to be really usable; Rodenstock, Schneider, Fujinon and Nikkor all have offerings in this length; the Fuji 125mm lenses are also good in this range if you don't need a lot of coverage. The coverage squeeze comes with the shorter lenses. I carry a Schneider Super Angulon 90mm f/8 (the larger, heavier f/5.6 is just too big for me), but if I were looking for my first 90mm, I'd look for the Nikkor SW 90mm f/8 for its larger coverage. There are tons more, but this will help you get started.
Filters: For really lightweight trekking/backpacking I carry only lenses that can take small filters. I have a 100mm Wide-Field Ektar that takes the place of my 90mm SA when weight is a priority. That and the Fuji A 180mm and 240mm gives me a 3-lens kit that is really light. All these lenses use or have step-down rings that take 52mm filters, so my filter kit can be really small as well. Normally, though, I'll carry the 90mm that takes 67mm filters and then an extra step-down ring from 67mm-52mm. My city lens kit is 90mm SA, 135mm Wide Field Ektar (bigger than a Plasmat but more coverage for the front rise I use a lot), Fujinon 180mm and 240mm. My hiking kit in the States is similar: 90mm SA, 135mm Plasmat (smaller and I use fewer movements with landscapes), 203mm Ektar and 300mm Nikkor M (on the top-hat board).
Sorry this got so long, but I hope it helps,
Doremus
