Well, I was lucky enough to find a used copy on eBay for $99 plus $5 for shipping. Although most all of the discs have smudges (fingerprints?), minor scratches, etc, I'vehad no problems with the discs at all - at least of the first season. And besides a seam-split of the top part of the box (which is covered up when the box is closed, anyway) the set is in practically new condition.
So, overall, it's extremely worth it.