It sounds as though you are trying to determine value of your home in anticipation of selling. If that is the case, I recommend that you have at least 3 (really recommend 5) real estate agents give you a market analysis of your home. Agents do this for free for potential customers every day. If you are able to have 5 agents come through for a market analysis, then throw out the highest and lowest estimated sales price (one is looking to buy your listing with a very high list price, the other is looking for the quickest sale), then average the remaining three. When (and if) you decide you want to list your home, go with the agent that you felt you could trust (regardless of their recommended price) and list at the price you determine.
In determining the value of the home, an agent or an appraiser, takes into consideration the physical condition of the home, the number of bedrooms, baths and other amenities (such as garage, lot size, view, etc.). They then compare your home with other similar homes in the same or similar neighborhoods. Just averaging the sales price of homes in the neighborhood will throw your numbers way off. A single level home compared with a mid-entry (as an example) is comparing apples to oranges just as comparing a 1200 square foot home with a 2500 square foot home would be inappropriate.