Been there before...
I moved to Cyprus for a while thanks to my job and needed to sell my car before i left. it was a Fiat Punto (i know....), eibach suspension, 17'' alloys, M3 mirrors, custom fitted pioneer stereo system, full fiat service history. Plus the original wheels and suspension that came off plus to save me moving it all the polish, wax, tyre dressing, pumps, tools the works. As i needed the car till just before i left it was £500 under the book price in Glasses guide and the car was immaculate....
Had some kid turn up and try to knock £1000 off the price, came back with his dad who tried to haggle again. Once the book price was pointed out to them and all the extra kit they finally (after 2 hours of crap) agreed to the price i had it up for. When he collected the car his friends mondeo estate was full to overflowing with all the extra stuff i basically gave away with it!!!!!
Should have charged him more. Some people are just chancers.