As a moderator I often chat with people (they'll call, message me, etc.) wanting to know about what prices to offer on properties.  The conversations are something like "I am making an offer on a property that is listed for $0000 but Zillow's estimate is only $ 0000, so I made the offer based on Zillows estimate and lost the property to another buyer, why? 

It's important to understand when looking at such sites, or when posting on Biggerpockets, etc. that every region of the country is different, on down to every city, neighborhood etc What Zillow and others often don't factor in to its figures for cost per square foot, and can't, is the specifics of the property. Make sure you are comparing apples to apples. For instance: 

• What s the age of the property?
• What size is the structure?
• What is the condition of the house, apartment, or ?
• What finishes does it have ?
• What is the square footage?
• Number of bathrooms? 
• What is the kitchen like? 
• Does it have a garage (single or double)
• What is the lot size? 
• What is the neighborhood like? 
• What is the local economy? 
• Is there a high demand for rental housing? (Even if you're doing a buy and hold, that will help determine the potential for future appreciation)
• If a property seems priced to high and there are not comps to support it, do you automatically pass, or ask, do they know something we don't? Have all the lower priced houses sold to people coming in to rehab and will be remodeling and returned to market at a higher price? Could it be it's a very popular area and fewer homes tend to sell? 
• ALWAYS ASK WHY? and find the answers for yourself. 

The point is, there is no short cut to doing due diligence. Sure, it would be great to have a simple program that answered all our questions. But... there is no substitute for doing your homework.  In the meantime, if someone could come up with a program where you can input all that info it would be great!