One option is a quality market analysis from a real estate professional. An appraisal, just as a real estate agent, can tend to look at the low side or high side. Condition of the home will make a big difference.
You can call me and I can give you more suggestions.
The assessed value and the appraised value don't always match. Myself, I would contact a local appraiser and have them review the other appraiser's findings and see what they say. But what can make the appraisal carry little more weight is the type of license that the appraiser holds. There are three types of Appraisers in your state.
1.) Licensed Appraiser that requires the least amount of education.
2.) Certified Residential Appraiser, which require more education.
3.) Certified General which requires double the education requirements as first one I listed.
Best of Luck!