Under the tax code, every dollar you receive is presumed to be taxable income unless you prove otherwise. If audited, I think you would have a tough case here.
However, this may not be self-employment income. If you are "engaged in an ongoing trade or business" this is self-employment income. You must pay income tax and 15% self-employment tax on the net profit, but you can deduct legitimate and reasonable business expenses. If this is a hobby, you don't have to pay SE tax, but you can't deduct your expenses.
More on hobby or business is here.
https://turbotax.intuit.com/tax-tips/small-business-taxes/when-the-irs-classifies-your-business-as-a...
If this is a hobby, you report it under other uncommon income, using any version of Turbotax. If this is a business, you need a schedule C, and you have to use Deluxe or higher. (If you are filing online and you want to deduct expenses against the income, you need the Self Employment version.)
