Unfortunately, in any way and by anybody.
First of all, I would like to present the relevant sections of the valid wording of the Civil Code:
§ 1684
(1) The purpose of an estate inventory is to establish the estate assets and to determine the net asset value at the time of death of the testator.
§ 1687
(1) If justified by the circumstances of the case, the court may decide to replace the estate inventory with a list of the estate assets drawn up by the estate administrator and confirmed by all the inheritors. If the estate administrator has not been established yet, it may be appointed by the court for that purpose.
(2) In simple cases, the court may decide, provided that the inheritors do not oppose it, to replace the estate inventory with a joint declaration of the inheritors concerning the estate.
I would also like to present the interpretation of these paragraphs by the President of the Notary Chamber of the Czech Republic:
The current price of the left property is ascertained during the inheritance proceedings, i.e. the price at which the property could be sold at the time of death of the testator. If there are no disputes among the inheritors during the proceedings, no high debts, or the survivors do not require an inventory of assets, then the property is usually appraised by the consent of the inheritors or from the appraisal carried by the estate administrator. If necessary, an expert's report will be prepared at the inheritors' expense,” said Radim Neubauer – the President of the Notary Chamber of the Czech Republic, for novinky.cz, 7 May 2017
There is no reference to Act No. 151/1997 Coll. - on the valuation of property, but the President already uses the term current price of the left property. The law speaks of the net value of the property, without specifying further investigation procedures. And finally, § 1687 gives notaries the opportunity to appraise the estate in any way.
In practice, the notary acts as a judge of the first instance in the inheritance proceedings and if there is no dispute among the inheritors, they can appraise the property themselves, even by looking out of the window. Some notaries require at least an assessment made by a real estate agency. Other notaries are more cautious and, instead of a real estate agency, they use an appraiser with a regulated trade who can and is entitled to set the current price. If there is a dispute among the inheritors, the notary will use an expert witness, which is also correct.
It would certainly be appropriate to amend the Civil Code here in order to have a uniform procedure for estate appraisal in the inheritance proceedings so that the law is the same for all inheritors.