How do you determine the asking price for a piece of property where you don't live, as in an estate?

My sisters and I have property near a lake but not waterfront. We had it appraised a couple of years ago, but the realtors say the appraisal is no longer valid because of the market. Is there a formula to figure by tax value what a reasonable price would be? Where I live people are asking 2-3 times the tax value. Does that sound right? I have no idea about comparables in the area.