It sounds like you mean it is priced over the tax est. value. Yes is could not appraise, but it could be renegotiated after the appraisal. Some towns are low, others are over priced. Get a good Realtor to help you price a good bid.
Please explain your question, the listing price and the asking price should be the same thing. Are you possibly saying that the listing price is above the assessed value? This happens all the time because assessed value is not always up-to-date and the property could appraiser for more than assessed value.