It stores the 30 in your satchel, and to my knowledge, there's no way to hold/store more than that even at your camp.
That said, even the initial $15000 you can get from 30 bars is a game-changing tremendous amount of cash. I bought basically everything I wanted at this point in the game for myself, my camp and my horse and I'm still at a little over $12000. Yeah, some will say it's lame to exploit the game in this way, but personally, my enjoyment of it all has skyrocketed without having to micromanage money and resources to purchase and stuff, and having fast travel sooner rather than later. I can't say I'm really into that kind of management in games, to be honest.
EDIT: Also, for the glitch to work, DO NOT take the horse pamphlet!