It's interesting reading certain other "dealers" reports (not pointing anyone specific out, and not trying to make a negative post) but sellers that are detailing for example, con costs of $1000, they've sold $1500, and consider that a $500 profit. Not taking in to account the cost of the inventory to begin with, or other costs, or losing two days sitting behind tables.
For many I think, selling is just an extension of their hobby -- the hobby is to acquire comic books. The selling is just a way to continue to do that.
Nothing wrong with that! but less business-savvy readers may think that this is an easier way to profit than the reality is....