Are you trying to lower the prices down to normal values?
You might be able to do it with Wrye Bash and a spreadsheet. Use Wrye Bash to export the item data from the mod you are planning to merge, then use a macro in the spreadsheet program to reduce the values, build a bashed patch with nothing but the original mod and the imported corrected prices in it and then merge the bashed patch into your mod after stripping out any unnecessary things that might creep in.