As far as the bad reputation goes, that came for the most part from an idle Pinto being struck from behind at a high rate of speed by a larger vehicle. I've heard of the same thing still going on with modern Crown Victoria's, (State Police vehicles parked on the side of highways), and the move by some states to switch to Dodge's. Would any vehicle stand up in such a scenario? Kind of hard to say. Is it possible the same could happen to your vehicle? Yes it is, although I think that the later year Pinto's had more beef in the rear suspension that the early models, and I think that the early models is where the problem manifested itself.
Affordability depends on your budget. I'm aware of how much college textbooks go for. Considering the age of the vehicle, it probably has had all of the regulars changed over the years, (brakes, water pump, starter, alternator, shocks, radiator, heater core, etc) , and some of these may need to be changed again.
The first thing that I would look at is the front suspension and what condition it's in. That may be pricey to repair but I think that you still may be able to get all of the componets. It's nice when the vehicle goes where you steer it and the front wheels don't fall off.
Brakes and shocks and tires would be my next concern. From there you could go into engine and transmission issues that could go into orbit depending upon the seriousness of the problem, but generally you can notice potential concerns with a test drive. For a hundred bucks you can't say too much.
Once everything is ready for the public highway, it is a very reliable vehicle that is sure to bring fond memories when your older. Gas mileage should not be a problem with a tuned engine, new fluids and filters. It is one of the most fun vehicles to drive, (with the rack and pinion steering), that Ford ever made. The only vehicle I have ever owned that I bought brand new was a 73 Runabout.
A note of caution in extream rainfall, and deep moving surface water,(especially if your moving with it, in the direction it flows), they can and do hydro plane and the rear end will slip out right underneath you so you have to slow down.
Hope this helps.
Al