Do I need work experience for doing PG in MS? What will be the total expense for doing MS degree from USA?

No, work experience is not required for MS, you just have to give your GRE and IELTS/TOEFL for the language test. Almost, in every university, there are various programs such as assistantship and administrationship which almost cover your tuition fee and they also provide some stipend to students. H

There is no need for the work experience to pursue M.Sc from the USA. You just have to pass TOEFL exam to go abroad. Fees/expenses may vary but for this, you have to spend approximately 15 lakhs (in rupees) or above.