Any company, irrespective of the size can go for ISO Certification. You can go for this even if your organization is run by just 1 staff.
For brand building, to be eligible for tenders, to acquire more clients, to improve efficiency and to reach to international clients.
The cost mainly depends upon number of employees in your organization, your products and services.
The certificate is issued from a premium certification body and it can be verified from its accreditation body website.