Let us start with the observation that it is likely that the camera you can buy in that price range will probably not be an interchangeable lens camera, although there are a couple of exceptions to this, but those exceptions may also have "other considerations" that may preclude their selection as your camera. One obvious camera type in that exception category are those FSU cameras where questions of camera reliability often come up. That leaves us with the "fixed lens" cameras that were very popular back in the 1950s, 1960s, and less so going into the 1970s.
While there are many who may suggest such things as the Rollei 35 or 35S, that will probably be above your price range. Other cameras like that include the Olympus XA and Epic, some Konica with their Hexanon lenses, the Minolta Hi-Matic 7s II, and a few others that should be less expensive. However, for your class, I would suggest something like the Yashica Lynx 1000, Lynx 5000, or Lynx 14 (I like the Lynx 14), or the Minolta Hi-Matic 7 (the original large one) or the Minolta Hi-Matic 9. All of them have better lenses than their smaller more pocketable counterparts. They also have a greater range of lens apertures and shutter speeds. While my preference is for the Minolta Hi-Matic 9 due to its greater versatility, the next close choice for me would be the Yashica Lynx 14. These larger cameras also have more mass that helps in holding the camera still when releasing the shutter and should give you a sharper negative with less hand shaking.
One real advantage for these older rangefinder cameras is their very quiet in-the-lens leaf shutters with a very discrete little "snick" when released; much quieter than the mirror movement and shutter of an SLR. The most common lens focal length will probably be about 45mm which can be pre-set easily in a "zone focusing" mode. This also helps with quick shooting, but the rangefinder systems in the viewfinder really are pretty good. For some applications, you may find that you will prefer the rangefinder over the SLR.