On a 2007 YTD basis, actual average closed prices for all types of housing on a consolidated basis (condos, townhomes and single family homes) have declined approximately 8% in Howard County. The largest slide happened in September, and probably is representative of price reductions following the end of the summer buying season.
If you would like to see a graphical depiction of these stats, please drop by my website.
In Columbia in particular here is each zip code for August 2007 vs August 2006:
-1.19% for 21044
-4.64% for 21045
-5.00% for 21046
Columbia is not doing as well as other parts of Howard County, say Ellicott City 21043, where home prices are up 5.52%. Columbia is essentially fully developed. The others parts of the county have an increase in average sales price due to higher prices of new construction homes.
Understand these numbers also fluctuate from month-to-month...let's look at July 2007 July 2006
-6.20% for 21044
+5.02% for 21045
+.62% for 21046
21043 still did well up 12.80% in July 2007 vs July 2006.
All data is from the Realtor MLS - MRIS.
Let me know if I can help you further.