Instructions
Make a list of each of the items you will need for your build.
Purchase one of the items you need for your map, then set it anywhere. You do not have to worry about placement until all the pieces are on the map.
Press "X" while hovering over the item and set the "Run-Time Maximum" to one number higher than the total number of that object on the map. For example, place a simple block, press "X," and set the value to "2."
Continue adding building blocks, changing the Run-Time Maximum value with each one. As long as you change this value, you can add as many objects as you want without worrying about the budget.