We made a cheeky low offer that was rejected, and the estate agent asked us to come back with our best and final offer. There are no other interested parties that we know of. We don't want to pay more than we have to, obviously, but we don't want to shut the door on further negotiations. Tempted to put in another low-ish number and pretend that it is final (although I'm rubbish at lying!). What is the best tactic?