Over 300 square feet is way too much.

Even it is from the County record, but it is their house and it is them to sell the house, so it is their responsiblity to give you the right information. Ask them if the county's record is 300 square feet smaller than teh actual size, are they going to sell it cheaper? County is not responsibal for this either. Tell them either they sell you at cheaper price or give you the earnest money back, because if they sell to next buyer they have to tell the actual size is 3095. Otherwise you will sure them, before the lawsuit is settled, they will not be able to sell the house. After the lawsuit, they still have to sell it at the size of 3095.