I made the mistake of getting a "good deal" on a totally rusted Pantera in 1989, paid $13K for it (well, $16K but got $3K in parts along with it.)
Another $40-50K later (I've lost count), and the car still isn't on the road.
If that sounds like your idea of fun, then go for it. But if you want to DRIVE a Pantera, you're much better off buying the best you can afford.
As a matter of fact, you're even better off buying the best you CAN'T afford. Figure out what your absolute maximum is, then look for and buy a car at least $5K more than that. You'll easily save $10K or more in the long run.
As far as I'm concerned, the overwhelming majority of Panteras (not counting the late-model cars, or cost-no-object conversions to GT5 or GT5-S spec) are $30K cars. You can either buy a car for $30K and be totally happy with it, or buy one for $20K, then turn around and spend another $10K to fix the things that need fixing. (Although, normally that car will then only be worth about $25K)
Take your time, sock away some more cash, you'll be happier in the long run to buy a better car.
Mike Dailey's website has an excellent analysis of the money he's spent on his car (although that might be a bit out of date now.) He also has an in-depth look at the critical rust areas in Panteras, along with some serious horror photos.
Mike (really, truly hoping to get my car on the road for good in 2002)