In reply to Crazier :
I am waiting for the clarification too. It sounds like Tom is about to turn things around from the way I understand it...
It seems like the sticking point is somewhere between here:
You may not list fair market value instead of purchase price on your budget unless you do not have a receipt from the purchase, or depreciation/appreciation has drastically affected the car or part’s value.
and here:
You may not factor gains or losses made from buying, selling or trading unrelated parts into your budget. You may sell or trade parts to yourself for fair market value.
So, the rules pretty clearly say you can't list FMV instead of purchase price, UNLESS you don't have a receipt. You don't have a receipt, so I guess you can use FMV. (Also says appreciation/ depreciation, but that is not your case). The loophole in this wording is that it seems to make an incentive for losing a receipt. No receipt= I get to use FMV. I don't think that was the intent (but it does exist). Maybe there is a case here for losing receipts on everything...
Then, the rules say you can't factor in gains and losses from buying parts. The loophole is that it says "unrelated". Your wiring harness did not come with the car, did not end on the car, and apparently was never really installed on the car, so it would seem "unrelated" to the car, BUT at some point in the middle of the project, it WAS considered for the build, which makes it "related". Sort of. This is a pretty loose interpretation, but its definitely a loophole.
Then comes the example..
If you bought an engine last week for $800, but the fair market value is actually $200, you must still add it to your budget at $800.
If, 30 years ago, you bought an engine for $800, you may add it to your budget at today’s fair market value if you desire to.
The first part of the example doesn't help you a lot, because it assumes you OVERPAID for the item, and therefore DO NOT want to add the purchase price to your budget. That's not allowed. But it doesn't consider that you UNDERPAID, and would LIKE to add it to your budget so you can trade it and add a "gain" to your budget. This seems to have been disallowed previously, if it wasn't for the "unrelated parts" loophole. Since your part may be "related", all of the "thou shalt nots" seem to be over-riden.
The second part of the example is clear as mud, because it says you can use FMV "if you desire to".
Between "losing" receipts, defining "related" parts, underpaying to gain trading advantages, and the freedom to "choose" whether or not to use FMV, it's quite a festival of loopholes.
Gonna have to wait for Tom on this one. But I do understand what you are struggling with.