[atnels]

If you are fairly confident in your BB/100 rate, you can extrapolate this to figure an average BB/hour given the number of tables you play and your average hands/hour. Combine this with the number of hours you average a week to figure out your net weekly income. Then look at your current roll and figure out what rate you would like to build up toward the next highest limit. The difference will be what you can nominally pull out.

Example: Say you figure out you're averaging 2 BB/hour over the past 20k hands and playing 25 hours a week. 2 x $6 x 25 = $300/week. If your roll is currently $2000 and you would like to get to $3000 in a month, then you'll only be able to pull out $50 a week.

This will obviously be much more accurate over a longer term since swings will play a large part in your day-to-day balance. I would use a calculation like this to give yourself a rough idea more than plan a budget - but it doesn't sound like you're in that position.