1. You can't e-file. Turbotax no longer supports tax returns where form 8283 requires signatures. Maybe a pro or another company. In that case, you would e-file an electronic copy of the unsigned form 8283, and then mail the signed hard copy to the IRS with a cover sheet within 3 days.
Also, you don't submit the detailed inventory, or the appraisal in this case, just the signed form 8283. Although certainly retain those items in case they are needed for audit.
2. You may have a problem with the qualifications required of an appraiser. See the instructions for form 8283. Your appraiser may have relevant experience, but they may not meet the letter of the rule unless they are regularly paid to do appraisals. They also can't be a party to the transaction. If this is literally the only person who is not a party who can attest to the value, make sure they thoroughly explain their qualifications, experience and training in the appraisal, and what standard and sources they used to determine the value of the items. There are some other statements that must be included in the appraisal. If they don't meet the letter of the rule, at least leave yourself in the best possible position in case of audit.
https://www.irs.gov/instructions/i8283#en_US_202312_publink62730rd0e1048
https://www.marcumllp.com/insights/new-irs-regulations-what-constitutes-a-qualified-appraisal
http://wagnerappraisal.com/IRSREQUIREMENTSFORAPPRAISERS.pdf
3. The appraiser can't be a party (the donor or the receiver of the property). If they were "involved" such as by helping you find a recipient that wanted your parts, but they did not buy, donate or were the ultimate receiver, that should be fine.
4. An overall assessment (but not value of each specific part) may or may not comply with the IRS regulations on the standard and practices required of appraisers, see the links above.
5. If you can't find a qualified appraiser or get an appraisal that follows the regulations, you will either have to limit your claimed value to $5000 or take your chances with an audit.
