Who determines that your re-sale value is $175,000?? You said in your answer that the "last home SOLD was $147, 837". Appraisers are not allowed to go back too far for their comparative data. 60-90 days is about the max. If the comparable homes that have actually SOLD in your area are under $150K, then that is where the market is for your house right now, at this moment in time. I agree with the previous poster that suggests you go back to the appraiser to ask them how they determined the value they assigned to your home. Its likely you wont change his mind, but at least you will have a better understanding of how he came up with the value.
There is a big gap I find in Trulia and Zillow and allot of the other sites online where they just throw out averages of homes...when was the data collected? Who collected it? These sites are good for basic information but for something as important as the value of your home, whether you are refinancing, buying or selling, its best to consult a real estate professional in your neighborhood. Good Luck!