I have an older Zeiss Ercona 1 6x9 folder that works well as well as a Balda Baldalux 6x9 folder that works just as well. Neither have rangefinders, coupled or otherwise, so I either shoot at infinity or use one of my old golfing rangefinders to guesstimate a distance. The Balda produces slightly better images only because the lens is a bit better but both can produce really nice images if the photog is willing to take his/her time. Both of these cameras were a little over $40 at the time but they both work great. I also have an old Agfa 6x6 that works as well. I got it for $10. The shutter speeds seem to be just fine. It does have some bellows problems but a little silicone and shoe polish keep things light tight and the lens is beautiful. The film transport is pretty simple but works just fine and there are no light leaks. The problem is with the focus, as with many Agfa/Ansco folders. For someone with less shaky hands than I, who is willing to disassemble the lens and clean the old green grease out, I am positive it make a very good shooter.
It all depends on what you want. Money does not make good images and a Leica is not necessary. I think the OP has a great idea and I applaud his gumption.
For $40 I recommend that you stay away from Agfa/Ansco folders unless you can live with temporary bellows repair and cleaning hardened grease from focus helicals. A new bellows will run about $70 so that blows your budget completely. Also, stay away from anything with a more complex film transport. The old red window is best for what you want. Look for one with two or three windows and ask if the seller still has the film mask, as the multiple window was usually a sign that a film mask was available. A sliding cover on the red window is nice but plain old electrical or gaffers tape will work just as well. Usually the simple shutters are less likely to have problems. 1 second through 1/200 or 1/300 seconds is pretty good for what you want to do I personally like the Prontor shutter but the Compur was usually considered a little more upscale. Coupled or uncoupled range focusing is nice, if you can get one at your price point, but again, that introduces more complexity and repair, though I find rangefinder adjustment easier to do than shutter repair. Besides, closing down your aperture to f8, f11 or f16 covers up a lot of small focus errors caused by guesstimation, and fits in perfectly with landscapes and cityscapes. The 6x6 format is a bit more economical as you get more shots on a roll. The film usually stays a little flatter as well because it isn't stretching all the way across that 9 centimeter acreage like a 6x9. Finally, most of these cameras will have a tripod socket though they may be 3/8 rather than 1/4 like the more modern tripod sockets. That's not an issue since adaptors are available. Besides, I have a little wooden platform with a quick release on the bottom that I attach to my tripod. Once leveled I can sit my folder on top of it and take my pictures at my leisure using a cable release.
Remember, a good 6x6 or 6x9 negative from a $40 folder will almost always put a good 35mm negative. Don't let anyone BS you, size does count. Good luck and have lots of fun.