Todd, first welcome to Lat-G, second just take an Excel spreadsheet and track everything there. You can set your goals for time, money, really any part of the build. You set it up to subtract money from the buget as you purchase parts right down to every little thing you buy just add to the line.
I'm making sound super easy, it does take a little time to set up the formulas but even if you don't know how to do it just google it and you will see thousands of videos of how todo any thing in excel.
Don't forget to start a build thread!