No experience, but I'd personally think of it this way: $600 is 15% of $4000, roughly the percentage you pay in fees selling on a platform like Ebay. Do you think you could make $4K in sales, and if not how much do you value avoiding the headaches of an online platform like creating listings, shipping, returns, etc. and how much do you think you'd enjoy the experience regardless of what you sell (that's certainly worth something). Don't know where you live but my experience at local conventions is that sets don't seem to fly off the shelves - I know I always see posted prices and assume I could do better online. Seems like one of those potential high risk/high reward scenarios where your success is mostly based on luck - how many people will show up looking to spend money (in an uncertain economy).