Really, there's no telling. So much of the differences between cameras, lenses, films, tripods are a matter of personal taste that whatever advice you get is going to have to be considered in that light. Some generalities might apply, though. For $400 you're most likely to find a monorail; wooden "field" cameras tend to sell for more than that. A Sinar F1 is one possibility. More often found might be something like a Calumet CC-400, a Kokak Master View, a Burke & James (B&J) monorail, etc. They all work pretty much the same and the "perfect" camera for you, if there is such a thing, will only emerge after experience. Ditto with lens: if you tend toward wider lenses in your medium format work then it's likely that you'll prefer them in large format but not necessarily. Don't worry about finding something the "exact" equivalent of your favorite medium format lens, though: that often doesn't translate all that well for some reason. Make your best guess, go with something inexpensive and try to learn lessons before you spend more than you're comfortable with. Take your time and you'll figure out what works for you, then next year you can be giving the advice to some new entrant! Have fun!