Chuck, value is going to have a lot to do with condition, but if a 95% five-screw Pre-17 goes for $650-700, you have to believe that a slightly better single-line model might go for a hundred more. I have seen boxed single liners offered at a thousand, but I usually think those prices are aspirational. The gun you describe, if in good shape but with the wrong box, could probably justify a price around $800-850. If you can get it for less, good for you. If the seller is asking more and won't come down, you probably have to ask yourself how much you want it.
You'll get other ideas on value, so average what you hear from all the guys who reply. That number will probably be in the ballpark.