An easy way to do this while making money as well is to always push for the 5 extra balls at the end of the round if you are very close to making at least one bingo. It doesn't seem to matter which location you are on. As long as you can form at least one bingo during the 5 extra balls. You will make enough money from the bingo to pay for the cost of getting the 5 extra balls.
The higher the location the more it costs to get 5 more balls. However you also get more money if you get a bingo. If you choose to take a second set of balls it is not very likely that you will break even.