As a final comment, it's worth thinking about that a "hobby" of selling tangible personal property will look very different on a tax return than almost any other hobby. If you were an amateur photographer and sold photos, you could consider the frames as tangible property that has a cost basis, but the travel, printing, advertising, and everything else would be non-deductible expenses. If your hobby was performing as Santa Claus at holiday parties, then none of your expenses would be deductible. If your hobby is metal detecting, everything you find is taxable income and you can't deduct travel or any other expenses.
Because we are talking here about the sale of tangible personal property, you follow the rules for capital gains property, and your gain is proceeds minus cost (if you can prove it).
