Although average home prices slightly dipped in Santa Clara County at the beginning of this year, January 2011 still shows the average price has gone up from the same month in 2010 — increasing 0.46%. During January of this year, average home price in San Jose was at $521,408 — a 2.97% decrease from December 2010, according to the National Association of Realtors. However, in January 2010, prices averaged at about $518,990. "Home prices in our region have gone up since the low of early 2009, but they are still affordable compared with historical data," said Mike Sibilia, president of the Santa Clara County Association of Realtors in a press release. "With the low interest rates, it's a good opportunity to buy, because a 1% drop in interest rates is equal to a 10% home price reduction for the buyer's monthly mortgage payment." The highest affordability index for Santa Clara County occurred in the first quarter of 2009, at 62%. The second quarter of 2010 is the ninth consecutive quarter with the index above 50% since the fourth quarter of 2008. Of the 44 quarters since 2000, the index was higher than 50% for 17 quarters. The percentage of households that could afford to buy an entry-level home in Santa Clara County stood at 57% in the fourth quarter of 2010, according to the California Association of Realtors. It is higher than the 52% for the same period of 2009, and more than double the 25% for the second and third quarters of 2007, the lowest since 2000. The minimum household income needed to purchase an entry-level home at $502,350 in Santa Clara County in the fourth quarter of 2010 was $77,400, based on an interest rate of 3.39% and assuming a 10% down payment. The monthly payment including taxes and insurance was $2,580. First-time buyers typically purchase a home equal to 85% of the prevailing median price. Write to Shaina Zucker.