Needs for ethics approval required on service evaluation for quality improvement in NGO? How to obtain ethics approval for small NGO?
Any reputable scientific publication venue will require some sort of IRB certification of almost all research involving human subjects.  There are certain circumstances where the data is anonymous or incidental enough to not need approval (see for example these US HHS decision charts).  Your research, however, sounds like it will definitely need IRB review.

You've already hit on the main avenues for getting review---partnership with university or contracting with a commercial IRB.  I would suggest a few others to consider:


Your country may have a governmental IRB or equivalent that you can work with.
There may be a larger NGO that you can partner with, which would be able to support IRB review internally or externally.
Some commercial IRBs might have a "reduced price" option for developing countries.


IRBs for research in developing countries are indeed a challenging issue: this document has a nice summary of some of the challenges and approaches.