@BetterCheddar
No matter what happens with the tax forms, you can be prepared by keeping accurate detailed records of your transactions. You should have a list or a spreadsheet that includes the description of the item, how are you acquired it as best you remember, how much it cost, the selling price, and any associated selling fees.
If this is an ongoing trade or business, with a clear profit motive, you may be required to file a schedule C to report this as business income. If this is a hobby, and you are not intentionally seeking a profit and you are not doing this as an ongoing or routine business, then you can treat it as a hobby. As a business, you can deduct other selling expenses like listing fees and shipping but you will pay self-employment tax. As a hobby, you can’t deduct any expenses, but you don’t pay self-employment tax. You should be prepared to defend your decision as to hobby or business if the IRS audits you.
