Here is this years chart so far of expenses vs. profits. I do two conventions a year. While the second convention does not have the overhead of production, it does have the overhead of travel and stay. Which is roughly similar to my production costs.
As you can tell, I am hemorrhaging money towards buying the artwork of other people and I am okay with that. Lion King, know what I'm sayin'?
Though at almost 600 dollars alone for a 8x3 table, it's pretty rough to bring in money for me.
If I were smarter I would quit making sketchbooks and stick to prints and commissions, but I like sketchbooks and comics. I like making them and I like buying them. Also, I should probably stick to an artists alley table which is smaller, but less expensive. Conventions the way I'm doing it aren't good for me from a financial view. I would need outside support to make this work for me if this is all I did.
I do ask myself the question if it costs so much why don't I change my behavior and solve the problem or stop doing it all together. The answer is A, I'm pretty busy and prints need to be in color to sell well for most people, and I really dislike doing color work. Then B, conventions are both fun and stressful in a way that helps me grow as a person. The experience has value to me, just not financially. Though financial value would be nice too.
Take away from this what you will. Next time you see an artist you like, buy something from them, cause they probably aren't rolling in it like you'd imagine.