I'm not sure what you mean by that. What conversion cost are you referring to?

banktivity said they couldn't convert your data, correct? This means you'll need to look for a third-party conversion service to help. Unfortunately banktivity is not a popular app at the moment and I'm not sure you can find a third party conversion service. Another problem is that there is no third-party tool that can export data from QB Desktop for Mac. So your options for converting data are practically non-existent. Starting from scratch in banktivity and accessing your historical data in QB Desktop is the best option.