Breakdown of course/site costs

[ECH90]

I have been reading all over the forums and getting a headache trying to keep information straight/up to date. Could someone confirm what different sites/courses cost? Am I missing any that have costs associated but are worth considering? Mapping out plans for myself and my husband and need to know the budget ahead of time 

Schmoop - $88/month? Only subscription I'm seeing that offers college credit. Is this for unlimited exams?

Davar - $25/course test

Straighterline - $99/month + $59 per course (also cost of time, with the massive, all encompassing textbook)

Saylor - $25/course

Study.com - $200/month with 2 exams and $70/additional exam 

I feel like Davar and Saylor are crazy cheap compared to the others and want to make sure I'm understanding these truly are the costs to obtain the credit, not just take the course and unable to ACE them for TESU. 

Is there any reason why either of us would NOT want to use Saylor or Davar for as many credits as possible? I will be doing a BALS (concentration in humanities or social sciences maybe??? Only if can fully test out and even then just because, no specific reason at this point) and hubs will likely do a BSBA-GM.

I also just applied for the Guardian Scholarship so obviously if I get it I'll take my free 6 exams (they are free right, no one is yanking my leg on that one?) and try to make sure they hit courses I'll struggle to find elsewhere.

Davar is $70/Course and a $15 testing fee per test i believe