20 homes have sold in Mercer County so far in 2014. The numbers are through March and are from the Illinois Association of REALTORS. The median sales price is $60,625. On average this year, it is taking 88-days for a home to sit on the market before a closed sale. There are currently 95 homes for sale in Mercer County. Last year at this time, 21 homes in Mercer County had sold with an average sales price of $80,000.