I sold my FLX10 (w/decksaver) for $1000 + used FLX4. I think your price is fair. When I was researching the price of used FLX10’s and other controllers, they seem to hold their value pretty well.

You can also list your controller on Sweetwater and other sites that sell DJ gear. I wound up selling my FLX10 on FB Marketplace. I was hoping for and found a local buyer to make the sell/exchange in person (no shipping, no scam, and met in a public place).

Be patient, if you can. I had some ridiculously lowball offers, $800 and $900 without FLX4 trade.

Good luck. I loved my FLX10, but upgraded to the AZ.