Dealers Profit Margin

Don’t forget that a dealer has to pay vat so the windscreen price will not all go in his pocket. Also he has to bear the cost of possible warranty issues so will make an allowance for that. 

I reckon your £30k is optimistic. 

Dealer may advertise at 35k but likely he will sell it for less.  They have to clean and service it and as TW says VAT, warranty and fixing any problems so I would say you are 2-3k off the mark.

Some dealers will advertise a vehicle on someone else's behalf  ..... 

Why not go for a brokerage deal, you agree a sale price and the dealer takes a fee. 

Trouble is with those there is not enough incentive for the dealer to push it, over selling his own vans on which his margin will be higher. We tried selling the late father in laws van in this manner and ended up selling it to the dealer before we would have needed to reinsure it.

Yes, much depends on the circumstances, how soon payment is wanted and the reasons for selling etc.

You could find a dealer who will act as a broker to sell your van.  I did this with a caravan about 4 years ago.  Paid a fix price which included, valet, display, advertising etc.,  Van sold in a month and I made nearly twice as much as I was offered for part exchange.  Might be worth you exploring

We have been down this path you may be looking at around £12000 - £15000 , we ended up selling it privately.

try Motorhomedepot..

Recently sold our van through Autotrader. Many dealers enquired and their prices was top teens, I took that as an average £18K. Selling privately I was asking £29K and got £27K. It was easy, Autotrader  web site very helpful with tips on preparing your advert. Warnings on Scams. How to take payment etc. Total cost £49.