One of the things that bothered me about the earlier Performance series speakers, particularly the bookshelf speakers, is that the grills are fixed (non-removable). Bring a good flashlight to check the drivers. Chances are they will be fine since the grills aren't removable (90% of driver damage is caused by the curious type that removes the grills and touches the drivers).
I've always felt that the Performance series looked a little cheasy, but they are solid speakers and they were real budget monsters in their day.
The subwoofer appears to be a PDR-12 version 1, which was the largest PDR subwoofer in the series.
The center is whatever went with the performance series (don't recal model) and has fabric on the sides for no reason that I can tell. The grill is removable on the center.
The front left and right appear to be Atom v.2 at the oldest.
For $350 it is a fair price. In the used sale market the total value of those speakers and subwoofer if in fair to good condition would be at least the asking price, probably more. I'd figure about $175-200 for the subwoofer alone. I've seen Atoms in good condition bring as much as much as $150 a pair in great condition. In fair condition about $100 a pair. You do the math, and it comes out to be a good bet. In the event you don't like parts of the system, or all, you can recover what you have in it.