If you learned just one thing at this conference that helped you optimize development by even a small percentage, this would be worth it. Or if you met one person who you could ping for specific questions when you hit a roadblock, this would easily pay for itself. I really encourage you to think about value, not cost.
That's a false economy though. You'd have to learn something that you couldn't learn by watching videos for free online or reading books for the costs to justify themselves and the networking would have to be better than you'd be able to do at other paid or free events.