New user question on Foreclosure's

Is there a general rule of thumb or formula that you guy use to determine what your final offer will be on a house that has been already foreclosed on, say they are asking 100k for round figures, how would you breake it down. Thanks in advance.

Gparcels,

    Banks are strange! I have offered way low just to write an offer and got it! And also have offered $500.00 below asking price and lost it! As a rule of thumb I always call Public Trustee and see what the bank paid for it and see if they are going to move on it! 

The funny thing is when I offer 70k on a house they own and are asking 100k and they come back at 98k I then counter at 60k when they call and say I went down I tell them I had to because they were not so someone had to!!!