Somethings to check on...
If I am not mistaken, a student has to belong to a program at my institution before PLAR can be done or before transfer of credits for a course can occur. So if you only take one course via OERu, none of the credentialling can take place. I could be wrong but sometimes there are more hidden complexities to investigate with respect to credentialling.
Plus PLAR is not "cheap" at my institution...I think it costs about the same as actually taking one of our courses...again, I could be wrong.