I have always found most dealers are prepared to haggle out a price before going to see them, often they are 3 hours away, and most get it.
Only ever had two who were not prepared to haggle, one was on an E500 estate up passed Derby, and the other was a 550i Touring near Knutsford. Both cars were pretty tatty when I got there, and not the sort of tatty that would polish or look better with a good clean either, scuffed body work, broken interior trim, worn switchgear etc.
So I came to the conclusion those that want you to go and see it first probably know there are issues that 'some' people might be OK with, but know full well most will not at the price they are asking. So if they won't discuss price before setting off then I just look at something else. But 99% of them will.
I can't think of many cars that I have bought where a deal hasn't been done on the phone or via email first, I always ask if there is anything I need to know about it, so I can get an idea of what I might need to spend to get it right, and they tend to be pretty open and honest. But then I don't expect a 10 year old car to be immaculate either, something that has driven 100,000 miles is going to have some issues, and you can't expect a dealer to drive round in every car they buy to try and find them, that is just part and parcel of buying a used car.
Also, if you want to buy a car 150 miles away you have to be prepared to drive back again if there are any niggles that need sorting, if you're not, buy one from someone down the road from you.
Herishi, I would stop looking on Parkers and What Car for prices, CAP is the one to look at, and even Glass's Guide, they show what they are changing hands for, not what some magasine thinks they should be changing hands for.
Januarys' Glass's has a Sport E320cdi estate on a 56 plate with 108k miles retailing at £9300, with a trade in value of £6480, you can deduct £1200 if it doesn't have comand.
An 09 plate with 72k miles on it is retailing at £13k with a trade in of 10250.