Personally I'd have expected you to get the Elegence for the price of the new Ambiente with no trade in. The 2007 car is ridiculously expensive, given that the road tax is going to be at the higher pre-July rate.
I bought a new Toyota in March, list price at the time was €21,780 which included metallic, delivery, plates etc. Got it for €19,900 cash including full tank and floor mats. 07 ones on the forecourt at the time were this price but I suppose they too would have been negotiable for cash.
Presumably you would get this type of discount for cash on a new Octavia.