87 5000 CS TQ Value

[rsdavis@i-link.net (Robert S. Davis Wetmore & Company: Austin Office)]

I am thinking about trading or selling my 87' 5000 CSTQ, possibly to get
into a new quattro. This car is starting to get expensive and I love it ,
however, it might be time. I could use advice on:

Longevity: This car has 147,000 miles, I am the only owner and have kept it
maintained well. How long can I expect (a guess) to avoid any major repair
bills?
Value: Where can i find it's value in trade and/or selling direct?
Replacement: I have always enjoyed my Audi's, (this is my third) and due to
cost considerations, I am considering a new A4 Quattro, any information
and/or comments?

Thank you for your considerations and comment.
Best....    rsd