Master's Level Computer Science Courses (One at a time)

[LevelUP]

I was hoping to get some suggestions.

I already have a master's degree. If I have 18 regionally accredited credits in computer science, I can teach Intro to Programming at the college level. I have a background in software development.

My question is -- where would the cheapest place be to do this one course at time? APU? I was thinking WGU, but they charge on a semester basis, so I don't think that would work.

Strayer? Or maybe the cheapest university in my state so I don't have to pay out-of-state tuition?

I was also thinking Statistics.com Data Science Certificate through TESU. However, the ACE credit recommendations are upper bachelorette  for those courses, so I was ... not sure how that would work.

If you only need 18 credits, WGU seems like you could do it in 6 months.  $3200

APU is $5130

Price isn't too different, I would take the quickest route. 

 I'm guessing you can't just take the ACE study.com courses.  You need to also be sure the courses you take would be considered the right computer science courses they accept.