Normally I would say to get The Best Spinner and use it to modify articles you already own. That way you can be using the articles and The Best Spinner while earning the points for Articlebuilder.net.
However if you have already earned one half the points for Article Builder it may not take you that many days more to earn the rest of the points.
So it is a hard decision to make and even harder to advise.
Personally I would get The Best Spinner and use it now but I have thousands of PLR articles on my hard drive that I received as bonuses. So I use The Best Spinner or Article Rewriter all the time.
I also use Articlebuilder on many of my sites so both are extremely useful. It is almost a which came first, the chicken or the egg type of question.
I have one selection of PLR articles that I am allowed to do anything I want with, including giving them away. They are on a variety of topics. If you wish email me and I will upload them to one of my sites so you can download them.
I have doctor appoints starting at noon today so it would be tonight before I could do this if you want it.
I want to congratulate you on earning so many points so fast. You must be helping a lot of people by answering their questions.