I think the 968 is unique and rare enough to be worth saving in the long term. I see it as equivalent to the 914/912 in the Porsche world. Under appreciated but still interesting enough to be valued by collectors. My own situation is rather unique -- as far as I know there's only one 968 Cabriolet in Chile and no easy way to import used cars, so I'm willing to spend quite a bit to bring it back from the brink.
In your case, if it's a runner and there isn't any body damage, $3K to $4K isn't bad. The power steering system can be fixed relatively cheaply -- if you feel like resealing it all yourself, figure around $500 all in. Sunroofs are known problems in these cars, and IIRC, the fix is easy, but not sure on price.
But there are gotchas -- flywheels are expensive in these cars ($800). The timing belt should be changed before actually starting the car, especially if it's been sitting for many years. You can get a complete kit for around $200 that includes the belts and all the associated rollers. The variocam mechanism should be inspected, the pads can wear and the chain can stretch. If the cams are missing teeth, you'll need new camshafts ($400 or more a piece). The chain and pads are fairly cheap though. The motor mounts are most likely shot, and those are $200 a piece. Cooling hoses as well will probably need to be replaced, $180 gets you a complete new set.
How's the interior of the car? If the interior color is not black/tan, you'll struggle to find replacement parts.
As for final value -- it depends on what timeframe you are thinking about. Over 10 or so years, my guess is that you'll probably recoup your investment, depending on the amount of miles the car has on it now.