"estimated" is used since the amount due changes every day and since lender is not sure exactly what day foreclosure sale will occue, the outstanding loan balance changes every day and therefore the number published in the paper or on Trulia is "estimate" only.
buying property at a foreclosure sale is not for "rookies"!
you need to pay CASH at the time of sale
you may not get a chance to inspect property before the trustee foreclosure sale.
you will be competing against people who do this (buy foreclosures at trustee sale) for a living.
there are plenty of foreclosure REOs that you can buy on the mls - properties you can inspect and make offers with contingencies.
.. reasons.....based on the type of loan you have etc..i would go to the source of the "estimated loan
balance" information that you received and question them more closely about the figures.