Changing listing price AFTER placing a bid.

[Curtis Deckard]

Hi everyone.  I recently put a bid in on my second rental.  From what my realtor told me the seller was "in tax trouble" and was wanting to dump some of his properties quickly so this property was listed at $24,900.  It cash flowed at $850 a month ($400 after expenses) so it was a great deal I wanted to jump on ASAP.  I took a look at it and met the seller.  There were two new furnaces and two new water heaters.  The roof was in decent shape etc.  So I put a bid in after doing my due diligence.  When it came time for a response from the seller, he said he had changed his mind and wanted $30,000.  Nowhere on the listing did it have $30,000.  Being somewhat of a newbie, my question is, is this legal or allowed?  I was thinking if a listing agreement is a contract, how can that be changed AFTER a bid is placed?  Any information would be appreciated.  Thanks in advance.