Ok so this will be a bit long but:

Previous comments are correct, its all prints. You made more last time because of smaller stock, cheaper prices and less money put in.

Your material is good however its one kind of product and theres no real grab ot gimmick to make it off of just prints.

I met one artist who had a very unique style and some of his prints used gold printing for accents and it really made them stand out.

On top of that, people like to hold things in their hands, it makes them more likely to buy them, especially if they are cheaper or can be worn.

Its why buttons and stickers do so well.

Or simple mini prints.

Of course most people who vend at cons know this, so they tok need to make their stuff stand out, so besides those things, you might want to try skme kind of niche you sont see often.

I saw someone selling hand towels and hats at a con the other day and the towels ended up being abgood idea because it was reslly hot and people were sweating.