A few thousand regular souls.
And I used the thing that upgrades your estus flask by mistake. It gives you five humanity, though, so I made sure to use it to upgrade some important bonfires. If I wasn't going to heal for more, I was going to make sure I had more of the damn things.
I'm level 47 now and the latest areas I've unlocked are the one with the ghosts that you can conveniently travel to with the elevator under the initial bonfire and the other is the poisonous town underground, which seems like they recycled a lot from Demon's Souls, but made everything way deadlier. I found both entrances to it - one of them is fairly straightforward in that you unlock the entrance after you beat the boss of the Depths (fucking sewer bugeye things). I actually found the other entrance by just exploring, and you can get to it from the cool Valley of the Drakes. I killed the poisonous dragon and got what he dropped, though - a dragon scale to upgrade the weapon I didn't have.
Oh well. There's always NEW GAME +.