Dealer Negotiation

Hi Guys, I'm after opinions.



I've been to see a car, didn't negotiate on the price of it (emotions got the better of me when I saw the car) and initially agreed on a part-ex price of mine to trade in. I put a holding deposit down and I'm due to go back to complete the deal later this week.



In between placing a deposit and going back to buy the car I've been to see a few other cars and the dealers have offered me £1K on top of what I'm due to get from the dealer I have placed a deposit with.



So basically I'm going to go back later this week but before paying the balance of the car I'm going to re-negotiate what I intend to pay for the new car and the extra I want for mine on trade-in.



I am right to do this or should I honour the initial agreement made when I put the deposit down?



I've sign a bit of paper that states the new car price, my part-ex price, the deposit payed and the remaining balance to pay so not exactly a contract of any type.



The deposit is only a 5th of the £1K extra I've been offered elsewhere as trade-in so I'm not too worried about loosing the deposit if I know I'll get that back plus more if I go elsewhere.



I really like the car and I do want it but don't want to loose out on an extra £1K.



Obviously this has come about in hind-sight and I now realise I didn't negotiate on my part-ex properly.



So, what would you do? Re-negotiate?



Thoughts welcomed....