Speaking from prior experience trying to sell 'modded' and then parting out, you will ALWAYS get more for parts than in total... just sad reality of how it is.
Twice now I've parted heavily modified Miata's back to stock and each time gotten 1000s (yes 1000s) more than when I was attempting to sell as a full modified package.
Race cars are just as bad (if not worse). If you are the one to build it from scratch, you have to go into it knowing you simply will never get close to your investment cost back. People I know invested over $40k into their 'race car' and then sold it later for $10k or less once getting out of the scene.
Even my former Time Trial setup SRT4, not a single person wanted to pay anywhere close to asking price with all my mods, so I sold off the mods for a total of around $4000, cut out the roll bar that was welded in and then sold the car 100% stock for more than I was getting offers for modded (just weid stuff but everyone seems to want a clean slate to do their own mods it seems)