So, the more interesting question is, how much bankroll to bring to a meatup, assuming you want to stay for the entire duration, and factoring in the variance of playing circus games??
As
@bentax1978 said, there is a ton of money running around at these events, but you really do not need to have your net worth on you to play all the games. I took two significant losses at the tables the week prior to BBotB and then two separate chip purchases materialized just before the event to cause me to think I'd be down to $800 in my poker/chip roll (which are one in the same for me personally). One of the purchases didn't work out, so I was alright, but I wasn't exactly petrified at rolling in with only $800.
As an indication of what's needed to stay in play, my itemized buy-ins for Friday and Saturday (didn't play Thursday):
$40 min-buy at .25/.50 game
$40 min-buy at .25/.50 game
$40 min-buy at .25/.50 game
$40 SOHE tournament
$40 min-buy at .25/.50 game
$140 Main Event
$500 buy-in at .25/.50 game
So even assuming I lost everything I put into play, I'd have been down $840 and I was playing every game at every second possible. And of course, there's no reason you would have to buy for $500 at any point, so if you did another min-buy, you could cut that total down to $380.
Just trying to say, it's very manageable even on a conservative gambling budget. And I promise you will get plenty of action on your $40. If you want to get it in 4 ways for $40 when you pick up a hand, you won't have any problems.
Of course none of that accounts for lodging, food, tossing Berg some extra money for the massive cost he incurs to run the event, but you get the idea.