how much would my ford orion be worth?

[Frank]

Hi, recently i bought a ford orion GL 1989, in mercury grey with electric windows, mirrors etc. it is standard and runs beautifully and i have the full service history, logbook and everything else that came with it as it only had one owner before me. it even has 3 of the original tyres still! apart from a small scratch on the front bumper and a small scratch on the passenger door the car is in great shape, no rust, the interior is also in great shape. I have been thinking about selling it but as it is an old car, (although hardly used with just under 40,000 miles on the clock) i am unsure what sort of money i should be asking for it. also some people have mentioned i should keep it a bit longer and it may become worth more. I know little about cars so any advice would be handy, thanks