You either have a business or a hobby. There are several deciding factors, but key is whether you run it as a business and whether you have a reasonable expectation of making a profit. If you regularly profit, you can probably treat it a business and file a schedule C including your income and expenses.
As a business, you can probably treat the credits as having no cash value. That means you have no income when you get credits. However, when you trade these credits for electronics with a fair market value of $1,000, you have a $1,000 gain. If you then sell that piece of electronics for $800, you have a $200 loss.
If you don't meet the requirements to consider this a business, then it's a hobby. The rules for a hobby aren't quite as flexible. You must itemize your deductions, and you cannot take deductions that exceed expenses in any given year. The logic would still be the same, when you trade "worthless" coupons for something worth $1,000, you have a $1,000 hobby gain. When you sell that thing for $800, you have a $200 hobby loss. The gains are taxable, but you can deduct the losses.
In your case, you're probably better off if it's a hobby as that means your income isn't subject to self-employment tax. Check the IRS test carefully and see if you can defend that characterization.
Check the IRS guidance to see if it's a business or a hobby. Here are the differences:
Business: You file a schedule C. You may be able to take some deductions for things like a home office. You don't have to itemize your deductions. You will have to pay self-employment tax on your profits.
Hobby: You must itemize your deductions. You cannot deduct losses in excess of your income from the hobby. You do not have to pay self-employment tax on your profits.