There have been 2 or 3 nice Spanish sidelock 12 gauges with comparable engraving/quality sold of of the EE in the past month for around the $600.00 mark or a bit less. If you are looking to sell, start at around $700.00-- $725.00 and be prepared to lower your price if there are no takers. You will likely find you will have to lower your price though unless you find that someone who really wants a 10 gauge double with fixed chokes which are very likely full and extra full.
After posting the above I see you already listed it at $700.00. Now ya just gotta sit back and see what happens.