You need to look it up by yourself.
Check the tuition rates on the websites of on the universities that offer an MBA.
Don’t forget that the prices differ for US and international students.

The cheapest MBA is offered by Eastern New Mexico University.

The price is slightly more that $4,000.

The program is online, and it is recognized by ACBSP (Accreditation Council for Business Schools and Programs), which is a government-recommended accreditation agency for business programs.

Get an MBA where you got your English.

Wharton School is the least cheap.

That’s not how it works for Master’s programs. You look for the cheapest Bachelor’s, but need not grudge money for the Master’s.

“The biggest cheap?” I believe you need to reconsider your decision regarding MBA. Really.