All 20 major metro areas in the S&P/Case-Shiller index of home prices reported year-over-year gains in January. Overall, the index rose 8.1%. Prices also rose from December to January, sloughing off the normal winter slump. In addition, low inventory and increased demand have led to a supply shortage in several areas. Some analysts estimate prices will increase 4% to 10% for the rest of the year as inventory remains low.