I may be biased toward the 94-95's having owned two, but they are great if you want that in between type of stang. You can't afford a 99+ GT with low miles, and fox's usually are beat up. I bought my car for $5,650 from a state auction 10 months ago, had to pay back registration of about $500 because the car was sitting in storage for 4 years undriven. All said and done I spent $6,150 for her w/46,000 miles on the clock, stock down to the air silencer with weld-in mufflers. I know I got a really good deal, but it is very possible to find a low miles 94-95 for the $6500 range as I did. And that was nearly a year ago, I'm sure the blue book value has gone down a couple hundred for the same car w/the same mileage. It has the easilly moded and strong 302, with updated looks, and cornering, brakes, seats, and interior the blow a stock fox body away.
The other route I would go is to do as my friend did, and buy a badass, rebuilt-motor/modified fox. He spent around 7K, and bought an 89 GT from a guy who used to work for maximum motorsports. Car has 275 fwhp, disk brakes all around, rediculous
suspension, custom paint, roll cage, cobra wheels, ect. Either way your going to have a very nice stang for under $6500 no problem.