Hi.
Because AC can't (as of now) introduce any kind of formula into schedules, you have a couple of options.
1. Instead of trying to do this inside AC, since you already have all data arranged, export it to a spreadsheet editor. Create a publisher with your schedules saved as TXT files (or xlsx files if they work for you) and link those to your spreadsheet, so you can update the information at any time by simply publishing again. I've outlined this method before, search in the forum. I has great benefits.
2. If what you want is to include those cost schedules in layouts, then you could add a couple of properties (via the new property manager) like cost and total (cost if you haven't already added the information somewhere else). You can then use the "Export property values from schedule" option to export the information as you have it in your schedules, edit those total values with a formula in a spreadsheet editor, and bring those values back with the "Import property values into elements" command (both in File->Interoperability->Element properties menu).
The first one will let you do whatever you want and need with the information, but it'll be outside AC and you will need to bring it back as a PDF should you want to include it in layouts.
The second one is a round trip, and including those cost estimations inside AC schedules is the only added value I see in this option.
Hope that helps.
Best regards.