It is true that conversion would involve substantial costs in staff training & IT system modifications also you need to overcome the employee resistance for change. Generally the conversion process would start with a gap analysis of the current GAAPs used & IFRS to identify the areas to be changed. You might have to outsource the gap analysis to an Accounting firm & they alone may charge a significant amount.
However the conversion, in theory, should result in cost reductions. Practically the costs reductions will depend on the type of the organization & the commitment of the management toward proper implementation.