The PT-92C (discontinued; they stopped making them in 1996 ) was replaced by the PT-917 which has some improvements in the design
The 917 adds a decocker, and the grip size is the same as the full sized PT92. The PT917 has one-inch shorter barrel than a 92, but there is no benefit to it because the 917's size overall is the same as the full sized 92
So, the PT-92C Compact is fairly rare, but not rare like a collector's item/in demand rare.
In 2005 they were selling used for $275-325
Current Prices:
I see a few each month for sale on Gunbroker, Gunsamerica and other auction sites, priced about 275-450 depending on condition and stainless or blued.. Cheapest i've seen lately was $200 on Gunsamerica, Most I've seen it for is about 475 for an unfired new-in-box Stainless on an Estate sale. Last one I saw for sale was Stainless very good condiion in Florida with 2 mags for $330. last month.... Here's a blued one more recently that didn't get the $300 reserve price
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=147536175 and here's a recent Stainless that sold for $352.
http://www.auctionarms.com/search/displayitem.cfm?itemnum=9496185
And a very recent one in Florida (they sell a lot in Fla)
01-08-2010 PT-92C (Jacksonville Fla)
Shows some minor wear marks around the trigger guard. It has the Pachmyer grips comes with 4 15 round mags and three different holsters plus a plastic case. $350 SOLD
I like the 92C better than a 917 because it's smaller/shorter grip (though it's still fat, same as mini-glocks are).
Taurus was just before their time on this one, but now that more people have concealed carry permits, they should bring it back IMHO. However, most people want a thinner single stack grip for concealability, so that's where the market is headed now.
If yours is Stainless and you decide to sell it some time, let me know.