Theoretically a Private Pilot Certificate can be issued on the basis of your ICAO-compliant country's Private Pilot license at no cost, just a paperwork exercise. These days however, the FAA needs to do special verification of your license with your country's issuing authority and they (the country of issue) may charge for this service.
As for Instrument, Commercial etc. it would be really tough to give accurate numbers since it depends greatly on where you go for your training, who you have as your instructor and how proficient you currently are in flying.
Ray