Gypsum and POP false ceilings will cost Rs 55 to 75 per sqft and will need ~5 days to install. PVC false ceilings are moisture resistant and cost Rs 100 per sqft and will need 2-3 days to install. For offices, we would recommend gypsum ceilings for aesthetic reasons.
For designs you can refer to freshhomez.com/false-ceiling-designs and also look at a video here