itonewbie
Level 15

Your client should be providing the valuation and a quick Google search will find plenty of guides out there, many from charities that accept non-cash donations.  Here're a few examples:

https://salvationarmysouth.org/valueguide-htm/

https://www.ccmaine.org/docs/Thrift%20Store/ThriftStore_ValuationGuide_7_19.pdf

https://www.goodwill.org/wp-content/uploads/2010/12/donation_valuation_guide.pdf

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