There are two main problems people when it comes to getting posts a) don't have enough time to write them b) don't have enough money to buy them.
Well this solution solves both problems, you will be able to slash the costs drastically and it is very easy to set up as well.
The simple solution is hire a writer, but not from oDesk or Freelancer but from Hire a Filipino Virtual Assistant - Outsourcing to the Philippines | Home (no affiliation), you can easily hire someone who is competent enough to write BuildMyRank posts from here.
You can find people to work for $400 per month and still work 40 hours per week.
The numbers will explain why this method is effective, this is how far you get with $400 normally, assuming that one post BuildMyRank post costs $1.5 ($0.01 per word).
$400 / $1.5 = 266 BuildMyRank Posts
Not bad, but if you assume that one BMR post takes 10 minutes to write. And 10 minutes is being slow, that is only 15 words a minute. Then it means that an hour is basically worth 6 BMR posts.
If you hire someone for $400 per month to work 40 hours per week, that means a total of 160 hours per month, and if 6 posts equals 1 hour...
160 x 6 = 960 BuildMyRank posts
That is enough posts to reach the maximum BMR post quota with 3 sites for 1 month as well. Baring in mind that the calculations assumed that it takes 10 minutes to write a BMR post, if you halved that to only 5 minutes per post (still just 30 words per minute) then you get 1920 posts for $400!