No harm in posting the schematic (preferably as an fzz so its readable in frtitzing) the spreadsheet may be more difficult as the forum only accepts some formats. If it won;t upload you could do it like we do for svg files and rename the file to fzpz (which will upload) and tell us to rename it to whatever for use after download. If cost is an issue, I expect that a pro mini is going to be much cheaper than doing an assemble your own CPU, but we will see 
Peter