For the most part the prices here on Trulia are accurate, especially if it is a home that is actually on the market for sale with a realtor, or one that a property owner has posted. As stated already, those that are RealtyTrac, I have found to have plenty that do not properly reflect the true market price.
My suggestion would be that if you wish to know the prices of homes in the areas you are looking for, you will want to work with a realtor that will have the ability to forward you accurate information straight from the Multiple LIsting Service.
Good luck with your search.
RE/MAX Advance Realty