Whatever someone will pay for it. it's not a Gen 1 and has the factory optic on a polymer rail. The optic is so so and the polymer rail is not the greatest. I would expect somewhere at or below the $1.8 k'ish price. The FS2Ks are not made anymore so this is a good thing for pricing.
I remember the 9000 number of the FS2Ks made from spare parts from a suspended contract. Those sold for around $1450 IIRC.
So somewhere around $1800 to $2000 is where I would start. You can always ask for more and lessen the price if it does not move.
Look at the completed (sold) transactions on Gunbroker for your set-up. The median of the selling values will give you a good idea of the value. Auctions are the best indicator of value for discontinued items without an active secondary market.
A FS2000 Standard sold for $2,500 about a month ago on Gun Broker. The tactical model usually sells for a couple hundred less around $2,200. I've seen tactical model sell much higher with a very low round count up to $2,800. It really just depends on the collector, political environment, discontinuation and sadly hollywood movies and video games.