A lot of people always want to really complicate this issue.
If you plan on selling on ebay regularly moving forward then you want to classify yourself as a business and use schedule C. It is the easiest way to do it, least likely to trigger an audit, which itself is incredibly unlikely. People in the general range of income that most ebay sellers tend to have face the fewest IRS audits statistically. The IRS likes to audit high income people and those who report almost no income at all.
Even in that sub-1 percent chance of an audit it is highly likely that the IRS will either accept your estimates, bookkeeping and records or only have problems with small things. It does not mean that you will simply owe full tax on a $20,000 comic collection as if you found it on the ground for free.
Sometimes I get the feeling that very few people who actually sell things on ebay, make a profit and pay their taxes answer these questions, as you always get 20 people telling you to hire an accountant as if ebay seller bookkeeping was some mystery, while others will start talking about capital gains or losses which is a highly scrutinized route that is not a great choice for someone with a general collection of old stuff that they have no real idea of cost basis who also definitely seems to be selling things for profit otherwise as well. I see new steam games and recent toy catalogs and such in your store, you are already operating in a for profit manner with that stuff anyway. Also, given your original stated value, the size of your store and the number of items sold I am betting it is going to take you years to unwind this stuff, and the schedule C paperwork is pretty easy. I do over 100,000 a year now and I just do schedule C on Turbotax, I don't hire an accountant.
