Self employed

@Kempenme20   

The IRS would like you to use regular receipts if you possibly have them, but in your case they do not seem to be available. 

Here is an article about selling information on e-Bay to distinguish if you are selling it as a business or as a hobby, it sounds like you are a hobby, but double check using these rules.

https://turbotax.intuit.com/tax-tips/self-employment-taxes/a-tax-filing-factsheet-for-ebay-sellers/L...

Here is an article that will help you if you did make a profit on a personal item and how to report it if you are not running this like a business:

https://ttlc.intuit.com/turbotax-support/en-us/help-article/sales-logistics/report-personal-items-so...

The other thing to consider if you are selling an item that you purchased and used for a business (small business, rental activity, partnership or S-Corp), if so was the item depreciated.  The basis of the product will be reduced by the depreciation or the bonus depreciation or the Section 179 depreciation.

If you are selling clothes from your closet that weren't used for a business, any items that are sold below what you paid for them or their value when you inherited them can be treated as non-income, but since they were personal items you can't take the loss.  Any items you know you are selling for a gain need to be reported, see the article above.  The remaining articles you will need to do as much research as you can as to what the actual purchase price was.  If it is an expensive item, you will need to seek an appraisal.