Capital gains are taxed at the lesser of 28% or your marginal rate for collectibles (note: has to be long term, can’t be a comic you bought and sold in less than a year). If you put your sales on a Schedule C you'll be at your marginal rate + self employment taxes (~15%) but you have a lot more options when it comes to claiming expenses that you don't have with capital gains, such as claiming your cell phone, internet, QBI deduction, etc. There's also the ability to lower your taxes with the Sch C by utilizing a self-employed IRA. You don’t need to set up an LLC or anything to do this, by the way.
Run the numbers both ways and see which way turns out better.