41 CFR § 102-42.50
What types of appraisals may my agency consider?
June 9, 2020
Your agency may allow—
(a) Written commercial appraisals conducted by an appraisal firm or trade organization; and
(b) Retail value appraisals where the value of the gift may be ascertained by reviewing current and reliable non-discounted retail catalogs, retail price lists, or retail Web site valuations.
[74 FR 2396, Jan. 15, 2009]