I believe you are talking about the prices on homes when you look at this site. It seems to be an indication of a range of market value for the home but I don't know where Trulia gets these figures. When you hire an agent, he/she should be showing you market value for either your home for sale or the home you plan to purchase based on the current market conditions specific to the home in question.
Think of the housing market like the stock market. It changes all day, every day. If we put a home on the market this morning for $100,000 but this afternoon 3 practically identical homes (location, features, updates, lot size, ammenities, condition and more) are put on the market for $90,000, you home is no longer well-priced.
If you want help buying, selling or investing in real estate in the Dallas area, I hope you will call me.
Brenda Kronenberg, Realtor
Keller Williams Realty