Look to see what a new one of the same brand costs. I would bet $1200 to $1500 is probably close. The manual angle option really makes a plow that size less desirable. I would start at 50% to 60% of new and see response. If you are not getting any responses to you add, include "reasonable best offer".
Also, find out how much to add a power angling system. That will help you sell it so people know what it will cost to make it so they will want to use it without climbing on and off the tractor to angle it. Information is valuable.......
Take GOOD pictures up close so people can see exactly how it works, etc. Post several GOOD pictures from various angles so people can really see it.
Also do some research so you know what it fits so you are advertising in the right category. If it will only fit one brand of tractors mounting system, that is a big drawback. If the mounting system is more universal, it will be easier to sell and command more money.
Include in the Advertisement and the listing title the brands of tractor it will fit. Many people search craigslist by the brand name of the tractor they are looking for attachments.
The more you know about what you are selling, the easier it will be to sell and you will command more money. Simply google the names on the plow and you will learn a ton. Also google a good picture of the plow and you may learn even more.....
A lttile investment of your time will put more money in your pocket in the end......It always does.
