Other than a functional watch, you need ZERO equipment to start TSD rallying. I did some rallies when I was first joined the local sports car club as a young man, got more interested in autocross and pursued that vigorously for the better part of 15 years. I recently took up rallying again. I'm really liking it. I still do some autocross, but the whole-day commitment for 6 minutes of fun is less appealing than it used to be, especially now that I'm married with a kid and a 6-day-a-week job. A good road rally keeps me mentally stimulated for a substantailly longer period of time. I feel it is a better value for the time spent, and $ for $ it is the most cost effective motorsport you can compete in. Entry fees are generally the same as autocross ($20-$40 an event) and you get to split that with your car-mate. You're only "consumables" expense is gas...well, actually gas, Red Bull, and Slim Jims in my particular case.
If you decide you like it, you can compete at any level, Regional to National, with nothing more than a ~$20 calculator if you choose the "stock" class. Having an older car can actually be a benefit in stock, since you can interpolate mileage between tenths on an old mechanical odometer much more easily than with a modern digital odometer.
New England Region SCCA has a Road Rally program. They only have one event so far on the schedule for 2010, but here's a link to their 2009 Schedule to get an idea of where around New England they may run again in the future: http://www.ner.org/rally/rdral/events/2009
Give it shot. Really, give it two or three. The whole thing is a little less "obvious" than autocross. Unless you start by riding with someone experienced, its probably going to take you a few events to get a good grasp of basic concepts and operational procedures . Unlike autocross, where the format is generally the same, there are a lot of potential variations in rally. There may be something about your first rally you don't like that may not be a part of any other rallies the rest of the season. So don't walk away after the first one unless you just hated everything about it. Once I got my wife through a few events, she actually started to enjoy it. We actually competed together in the United States Road Rally Challenge this year.