Like you, I suffered from photo GAS for quite a while but I was in the US Navy and had a good paycheck as well as a locker of gear I could play with since I was a photographer.
If you are even thinking of doing street photography, get a Speed Graphic, Crown Graphic, Super Graphic, Busch Pressman D or Wista RF. Out of those the Graphics are the most common with the Crown being the most desirable for weight concerns. If you ever would want to use a barrel lens though, you are limited to the Speed Graphic.
Don't think about a Chamonix because it has a ton of movements and is new and shiny and all. The Chamonix is a true view camera and you have to focus with the ground glass. This is not something that is possible for a beginner to do handheld.
I've been using 4x5 on and off since 2000, having started with a Crown Graphic with a known good rangefinder and a good lens. These days for 4x5 I shoot a Nagaoka which is a super-light field camera with full movements. I purchased the 4x5 specifically for its weight but at a cost of slightly shorter bellows so I can't use lenses over 300mm.
All these choices have their individual advantages and disadvantages.
The Crown and Speed Graphics have a reputation for durability and easy repair. I shot my university senior thesis book with a Speed Graphic that I was given then I fully restored. Watch out with the Speed Graphic because the focal plane shutter can be disintegrating. The rubber coating on the silk can be flaking off after these last 50 or more years. The metered gaps in the cloth can also be off and not parallel which would lead to uneven exposure on the frame. Sometimes the whole shutter blind needs to be recemented to the drum. All sorts of things can go wrong with these cameras although they usually are fine, even after decades of use.
The Crown is slightly lighter and shallower as it doesn't have a focal plane shutter. As such, it can take wider lenses than the Speed.
After I returned from Iraq in 2005, I was given a Crown Graphic shell without a lensboard or support. It sat around for a few years then I sawed it in half to shorten the lens registration and I made this camera:
It was a "point-and-shoot" 4x5 with a 65mm Super Angulon stuck onto the focusing helical of a broken Nikon 50mm f/1.4 lens.
Get a Graphic with a Graflock back, not a standard spring back. These will allow use of a whole range of film accessories. The spring back can only take standard 4x5 film holders.
The Busch Pressman D has a rotating back which allows you to shoot horizontal or verticals without turning the camera, This can be beneficial for a few reasons. The Busch also has a little bit more movement than the Graphics. The back of the Busch is not a Graflock back either, so take that into consideration. The Pressman cameras are excellent in spite of this small limitation.
The "ultimate" field camera with a rangefinder would be a Wista RF but they are well above that price range of yours.
I'd say like other members that you should concentrate on the gear you have but you're going to scratch that itch regardless of what any of us say. So, get the best condition Graphic or Busch Pressman model D (not the C) you can find, with a very good condition lens in a well maintained shutter. The basic 135mm Raptar by Wollensak will shoot circles around all but the very best Leica as long as the glass is in good condition and the shutter is working well. Also look for a 127mm Ektar in shutter.
You have to budget in film holders, a developing tank, a large changing bag, and of course, film. 4x5 is not cheap. You'll go through $50USD in film in under 50 exposures. So, that is why most large format shooters are a bit more contemplative and stuck to a tripod, waiting for the good light.
Phil Forrest