The $300 entrance fee actually makes it more of a Bitcoin elite/high society club. Why don't we "commoners" get together at Singlebarrel on San Salvador st Saturday night? If the lords & ladies of Bitcoin Abbey want to come too that's fine.
Meh... it's a bit pricey, but conventions tend to be. I just signed up to go to the LP of PA convention, which is way more minor than this Bitcoin conference, and the cost was like $115 or something like that, so $300 isn't TOO bad. Now, if it was $500 or more, THAT would be over-the-top.
Your idea of a "gathering of commoners" is still a good idea, though... if you want a less pricey gathering of many Bitcoiners, check out the Porcupine Freedom Festival up in New Hampshire (aka. "PorcFest"). Last year's PorcFest was, up to that time, the most Bitcoin-friendly event ever.
http://porcfest.com