88 homes are on the market in Mercer County. Those are the latest housing numbers from the Illinois Association of REALTORS. Ten homes sold in September with an average price of $95,250 and the average time it took to sell a home last month was 44 days. Year to date, 93 homes have sold in Mercer County in 2013 with a median price of $87,000 and the average time on the market at 99 days. Last year at this time, 92 homes sold with an average price of $85,250 and an average of 104 days on the market.