1. Go to the following website: http://www.realtor.com/.
2. Enter a ZIP code.
3. Chose Homes for Sale.
4. Enter your price range (the minimum and maximum amount you want to spend).
5. Enter the specifications (number of bedrooms and number of baths).
6. Hit Search.
7. Find a home that you like or would consider.
8. Go to the U.S. Census website: http://www.census.gov.
9. Click on the American Factfinder tab on the left of the screen.
10. Under the Fact Access to Information title, enter the ZIP code of the house you found.
11. You will get lots of data on demographics like age, gender, family size, education, income, and crime rates.
12. Find out the price per square foot for the house you found.

The goal now is to find a very similar house (age, lot size, square footage, number of rooms, and number of bathrooms).

Repeat Steps 1 through 12.

In Step 2, pick another ZIP code 20+ miles away from the first ZIP code you picked for the first house.

In Step 5, pick the same specification and choose a house that was built in the same year or so as the first house. Also, try your best to find a house that has the same lot size and square footage as the first house.