I have an AOR: AR7039 Plus, I was wondering how much roughly would be a good price to sell it foor. Looking online I think it would be around the £800 mark second hand but if I could have a second opinion it would help.
Look through past or current copies of Passport to World Band Radio. The editors usually give a price range for new items. This'll give you a rough market price for your rig as it sells new today. Prices are usually listed in $, £, €, sometimes ¥.
Also, try joining a listserv for your rig and ask participants what a good used value might be. Some participants might have sold their rigs recently.