I generally sell privately - I've even been upset with mates who trade their car in without offering me first option! The price that a dealer will offer you as a trade-in is appallingly low. That being said, if you don't have secure parking then don't meet the prospective buyer at your house. Meet them at a local service station or similar place with plenty of light. If they can't arrange a suitable time window to meet then they are not a serious buyer.
A mate of mine traded a 3 year old BMW 525 a few years ago. The market value was around $50k at the time. He traded it for $32k.... I'd have been happy to take the car from him for $32k and sell it privately for $45k making $10-12k in the process... from memory the dealer advertised his car for close to $60k.
Don't forget that the dealer has to provide a warranty, carry the cost of money, cover their overheads, pay a sales rep commission and make a profit. If they don't have a second hand division then they will flip the car to a wholesaler - who will add his own margin and sell it as stock to another dealer. When I bought my last *new* car, I was offered the usual low ball price for my Celica GT-Four - about $10k under private sale value. He also wanted access to the car immediately so that he could move it on and offered a loan car for the 2 weeks before mine was ready. I politely declined and ended up keeping the GT-Four myself and my girlfriend and selling her car instead - privately, to a mate.
(maybe a bit too public) or carsales here I come.
