Part Exchange is it still OK to negotiate on price?

[ShouldWeStayOrGo]

We are trying to sell but not having much luck (whole other thread!) and as we need to move we are looking at part exchange.

We are going to see one on Saturday which is a single house by a small local builder. The price is over what we would like to pay but if we are looking to part exchange can we still negotiate over price? The builder wants a 65% difference on our current house price but even with that we still have room to play with.

The other option is to look at cutting our sale price significantly to try and get a sale (we have already gone for a lower price than recommended by agent).