Just tell them you're looking at a couple of others, you like theirs, but you would like to know what they can do with the price, and keeping pushing down
I bought my '58 1.9 Lusso nearly a year ago, 3yrs and 1 month years old. 122k miles. It was listed at 5850, I said it was overdue a service (he posted me the service history). I hadn't seen the car but said I hoped it was as good as it looked.
I flew to Heathrow from Edinburgh and met the trader, on the understanding that I'ld test drive it going back to his depot , and if it broke down on the way back to Edinburgh he had to pay for the recovery and get me home and refund me. He signed the receipt 'pending approval' at my request.
(I had been looking for a high mileage ex-lease motor on the theory it was well serviced and had only been driving mostly in straight lines at steady speeds)
After seeing a few more stonechips than I would've liked and and taking the service into consideration I told him I wasn't going over 5400. The money I saved went on insurance.
I had got one dealer down from £7350 to £6650 on a 2008 Ti, but felt the cheaper car was the better buy
The secondhand car market is pretty flat. Dealers have mostly preregistered more new cars than they can hope to sell before the next registration number comes out (to meet minimum targets to maintain manufacturer discaounts) so the whole secondhand market will slip down a bit more next year.
A good seller (/dealer) will know that and will seriously consider the chance to move any car before christmas, January is always a hard month, and without money in the bank it's even harder.
EDIT - I just found this about it http://www.autoexpress.co.uk/car-new...-pre-reg-sales
It happened last time about 6 years ago. Basically, all of the cars which were pregistered have got to be sold as 1 year old cars soon. To be competitive the prices have to be low, so that puts a lot of 1yr old cars with very low mileage into the secondhand market....so all the 1yr old cars with 10k miles on have to come down in price if they are to be sold...and it has a knock on effect all the way down.