Appraisal before wholesale contact

[Wesley Hoover]

I have an attorney holding 3 properties in a probate situation. I have an investor interested in purchasing all of these properties at once and wants me to get them under contract. The attorney will not agree on a contract until an appraisal is done and says that he will not agree for anything less than 100% of the appraised value. Is this normal? Who should pay for the appraisal and when should I get a contract?