Using an old camera is a ton of extra work and not necessary. Guy Maddin, who specializes in replicating old film styles, shoots only video these days (and I recommend checking out his work as doing research on the many filmmakers currently making old-style movies to uncover their methods).
Having just directed a 25-minute 1920s-style silent movie on numerous locations for over a year-and-half worth of shooting, as well as being the film's editor, I can say with certainty that much can be accomplished during post-production. You can create aged effects with numerous plug-ins, you can adjust contrast and color to your heart's content, you can go crazy with various grain and film-look effects.
I'm not saying you should never shoot on film, I'm just pointing out that it's harder and much more expensive. Why suffer when you can replicate much of what's great about film on video? Video isn't film, true, but man, you sure can get close, and with so much less effort.
My other advice is that you should shoot in as high-quality as possible if you're planning to age a film's look. If you have high-quality source footage, you will have many more options available to you in post, and many more ways to "damage" the footage open to you. Don't confuse "old" with "bad" -- they are not the same thing.
