Colt's Manufacturing Company made two different series (the C Series and the F Series) of Second Generation black powder revolvers between 1971 and 1982 in their Hartford plant. They were assembled and finished by Colt employees using Colt processes and expertise from parts made by the Italian replica manufacturers. They are considered premium quality guns, much better than the Italian replicas.
The Walker was only produced in the F Series; the value could very well be worth the extra $300 or even more. The Fifth Edition of the Blue Book of Modern Black Powder Arms lists (on page 49) a 100% F Series Second Generation Walker as worth $1000, but as always, condition matters greatly. A 98% gun is down to $725, and 90% is $450. These guns were marked like the original Walkers. Most had 4 digit serial numbers, but some 244 were made with a 5 digit serial number; they command a 20% premium. In addition, there was a presentation model called the Heritage Walker made under the F Series that is worth about 10% more than the regular one.
A Third Generation Walker was then produced by another company named Colt Blackpowder Arms, Inc. Again, Italian parts were assembled in the US; many of the craftsmen were former Colt employees, and these guns are also considered premium quality Colts. They are distinguished a silver backstrap with Sam Colt's signaure, and they are known as the Signature Series. The values start at $650 for a 100% gun, then $525 and $415 for 98% and 90% respectively.
Of course, Blue Book values are a guide only. Actual prices can and do vary considerably, and condition is all important with these guns.
I'd say the dealer is being quite fair with you, depending on the actual model and condition of the gun he wants to sell you.
