Inside a zip code you will find many different markets and subsequently many different market trends. I work with these kinds of questions on a daily basis. I have seen properties increasing while others are decreasing. It depends on the core factors of the type of property you seek in terms of size, age, location, condition, updates, amenities etc. You really have to study trends on a home by home basis. Studying a broad zip code will give you a very diluted indication of what the market is really doing for the home you seek.
For example: 84092 offers you a wide range of values that are experiencing very different market trends. Homes that are $1,000,000 plus are most likely suffering while homes that are $100,000-$250,000 are stable. In 84092 you will find both of these values and mixing them together in one study will not give you the best results. Give a better idea of exactly what you are looking for and the trends are very easy to identify for that type of property and market.
Call me anytime 801-999-0201. Jared Anderson. As a Realtor and Appraiser I work in this market on a daily basis.
Also, there are currently 647 homes(single family) for sale in Sandy and 247 for sale in you preferred zip code(84092). The more homes on the market, the more leverage you will likely have when negotiating a price with the sellers.
Median Single Family Home sale pricing for Sandy(84092) in 2009
I hope this helps!