Do you have credit card receipts? Nothing at all? Online email order confirmations? If you bought your items from a department store, you might be able to go back and search through old orders too and take screen shots of the details.
Starting in 2022, if you think you'll go over the $600 reporting threshold, I'd start keeping a spreadsheet. List the item and all pertinent information that you can recall, to the best of your knowledge. The date you bought the item, the cost, where you bought it, where you sold it and for how much, basically as much information as you can recall. Even if you have no receipts, the price of certain items is well known so if you are selling a classic m/l Chanel flap that you bought new in 2017, it is pretty easy to prove that the cost in 2017 was $4,700 + sales tax in most cases. Then you can provide this spreadsheet to your accountant at the end of the year.
Thank you. I might have some receipts, but a lot of what I sell on TRR tends to be clothing, as I have managed to get my bag collection pretty pared down. Some of the dresses that I sell are at least three or four years old, so I don’t have the receipts anymore. I highly doubt any of it would sell for more than $600, but it would definitely add up to be more than that. I just sent them 41 items about a month and a half ago.
That being said, I do have a few contemporary bags that I need to offload, so maybe I will do that now.