Housing affordability is higher today than it has been for decades. What does this mean for today's buyer? It means now is the time to buy.

According to the latest National Association of Home Builders/Wells Fargo Housing Opportunity Index (HOI) data, 73.9 percent of all new and existing homes sold in the fourth quarter of 2010 were affordable to families earning the national median income of $64,400.

Today's report shows that housing affordability at the end of 2010 was at its highest level since we started computing the HOI, said Bob Nielsen, chairman of the National Association of Home Builders (NAHB) and a home builder from Reno, Nev. However, while this is good news for consumers, both home buyers and builders continue to confront extremely tight credit conditions, and this remains a significant obstacle to many potential home sales.

Are you looking for the best of the best when it comes to affordable markets? Indianpolois-Carmel, Indiana, is a great place to start. It was ranked as the most affordable housing market in the entire country. Ninety-three percent of homes sold in the city were affordable to households earning to area median of $68,700.

On the opposite end of the spectrum, Santa Cruz-Watsonville, CA, was ranked as the least affordable city in the country. Only 45 percent of homes were affordable to families making the median household income of $84,200.

Also near the bottom of the list, according to the NAHB, were: Ocean City, N.J; San Luis Obispo-Paso Robles, Calif.; Laredo, Texas; and Santa Barbara-Santa Maria-Goleta, Calif.

Nearly all of the lowest range major metrol areas were in California, which is not surprisingly considering the housing bubble that formed in the early 2000s.