I was on a waiting list for a set of manuals for my 993 on both Pelican Parts (
www.pelicanparts.com )and My-Porsche.Com . Pelican finally said that they could not get the manuals. My-Porsche could not get them right away, and lost my request. When I contacted them once more, they apologized and said that they would sell them to me for a mere $650 instead of $890! I turned down the offer, and ended up buying a set from eBay for $340. It still felt pretty steep.
Evidently Porsche does not publish the manual set all that frequently. About a year ago I watched a set on eBay get auctioned for $900 or so.
Some people have bought CDs of the manuals on eBay for not much money. I haven't seen them, but supposedly it is difficult to make out the wiring details.
You might try searching the 993 forum on rennlist.com for more info.
-John Ross
ps. Most people also get the Porsche PET (parts catalog on CD). I bought one of these from Sun Coast last October for $15.00