The rates change depending where you live, India could be cheaper. I also believe OU Uk has regional accreditation in the US, which makes them cheaper than my local alternatives that charge $29-40k for a BSc.
You change your country on their site and then look at tuition/programs or ask their admissions. For example Scotland residents pay much less or there's IGNOU which does online math degrees for 10k rupees a year (I actually tried to get in there, but my country refused, the materials are still pretty good/rigorous). No idea the accreditation for IGNOU but OU Uk with regional means can apply to US grad schools like that Georgia Tech online MSc for compsci.