What is the cheapest way to pursue undergraduate studies abroad?
Does that mean free education?
If you are thinking of free education, then you can think of opting Germany for your education, where there is no tuition fee but you might have to bear living expenses (approx 40-45k per month). Also, you will have to learn German language.
If you are thinking of studying in USA then you will have to apply for Scholarships, Which are abundantly available, yet, difficult to get.
Tuition fees of the universities for bachelors degree vary from university to university,
Refer the above link for more accurate details.
Hope this helps.