Don't worry, there are alot of cars for sale right now. I know alot of people are thinking the boxsters are now a good price (good price! ha, I would have hated to buy one new and found out in 5 years it's worth half of what I paid.
As far as the 87, I would be very interested if it was silver

It's a buyers market, and if I am going to spend over $30K for a second car it must be exactly what I want.
I too get the trader every thursday (have for years) amd I am seeing the same cars for 2 or 3 year for sale...some the owner is out to lunch for the price versus reality, the others are so specialized you have to wait until the one person that is looking for that exact car comes by. I know a guy selling a 993 targa that over 2 years has dropped his price by $12K and I bet he hasn't had one phone call yet.
Yours is a desirable car, and it looks like a good price, you just have to wait for mr. (or mrs.) right what they want to come along. It's the nature of our beast.
If you are lookign for a quick sale, sorry, the Porsche is too specialized for that. Drop it to $20K and bend over (not) I took 2 years to find my car, and I'm always in the hunt for my next to own, next to sell car