Beer is food.
Rob, I remember in my late teens going through the J.C. Whatnot catalog, trying to figure what it would cost me to put together a Fad-T Bucket.
After about a week, I discussed it with a high school buddy, and he started asking questions like, "What about a master cylinder?", and pointing out the cost of gauges and light bulbs. He declared my estimate wasn't even close. Then he pointed out a Bradley GT a mutual friend of ours had built, and how every time he turned around, it was another $20 or $30.
I'm not taking anything away from your accounting skills when I say I doubt you'll ever get an estimate down to within $1000.00 of the actual cost of parts and machine work. Things change midstream, advertised costs change or aren't even close to what you actually pay, shipping adds up, parts availability dries up, unexpected component repairs raise their ugly head.
Any spreadsheet of this nature will probably be of great value to keep you to
task, but I doubt if the
numbers are likely to hold.