Sellers are always motivated in different ways, and you should always negotiate on either price or terms.
Start by finding out which is more important to the vendor.
They might be looking for a quick sale because they have to move for work, in which case they are less fixed on the price and just want it gone.
In other cases they might have other reasons to sell, but really need a longer settlement, in which case you can negotiate the price down to accommodate their needs.
Put the vendors needs first, but leverage it to maximise the value proposition.