If you're looking for prior sales information, Trulia's got that for you. If you're looking for those values for Baltimore County, check out the link below. If you're looking in another area, perform your search in that location. On the search results page check the option to view 'Recently sold homes' under the Listing Type section and uncheck the other options under that section.
I hope this helps you! Please let us know if you have any other questions.