Websites like Trulia can't give you as accurate of an appraisal as a professional. The sites don't have all of the specifics necessary to do a complete analysis. Some considerations that need to be made by a professional, such as lot size, condition of home, specific location, etc. can't be made by software, it's too specific to one property. I suggest you work with a Real Estate Agent who can provide you with accurate values of any properties. Keep using Trulia to stay abreast of the market, but follow the advice of a professional.
We are in the trenches and know the market better than a computerrized service which looks at numbers.
There are many intrinsic factors that contribute to a homes value which a computer is unable to evaluate.
Besides, the lender will work with a realtor who completes a Brokers Property Opinion (BPO) . Thiis report is similary to an appraisal and helps the lender establish a price for the property.
All the best,
In general, all homes should have been from the same school district, city, zip code, style, bedrooms, similar lot size, foundation, year built, sold in last 90 days, and within 150 +/- above ground living sqft. There are many more value adjustments included on the website below under home styles and construction types.
I suggest finding out the homes used by the appraiser and comparing them to the ones you used. You can also try http://zillow.com http://cyberhomes.com or http://realestateabc.com to run some comparables. Again on these sites, you will need to make adjustments and not simply use all the homes that come up. By the way, with all the problems in the sub prime market, don't you think all values should be conservative? Be glad the appraisal came in lower.
Your best bet (in my opinion) would be to work with a Buyer's Agent. A sample contract is on the website below. Buyers' Agency requires an agent to work for your benefit and they will run comparable sales prior to submitting an offer.