You need to report your income accurately, even if the default pathways in the program aren't right for you. If there is not a good default pathway next season, come back here and we can help you deal with it.
Also be aware, sales of collectibles are taxed as ordinary income, not at the lower long term capital gains rate, although they are still reported on schedule D. Personal items sold for a gain are taxable, but personal items sold for a loss are not deductible. The 1099-k will probably report the total amount paid to you, so you will always need your own documented proof so you can report only the taxable gain, under the correct category, and not deduct losses, or accidentally report the proceeds as taxable.
