I've built stuff and modified stuff and in general people pay a lot more for original condition than hacked up modified. People who want DIY will DIY. People who want vintage value vintage. There is not a lot of crossover into people who value vintage and will pay more to not have that classic look.
Then again, because I have built stuff I know you can sometimes build something that far outperforms anything that could have been bought off the shelf. It won't sell for but a fraction of what it performs equal to, but if you get enough enjoyment out of it for long enough then it was probably worth it.
My Miller Carbon turntable was like that. Roughly $20k turntable performance for $6k, but worth only $2k used. The buyer said it was shocking how much better it is than anything else he's heard. So just be aware, and no matter how great what you build turns out don't expect anyone else to value it so dear. Even though in absolute performance terms it may be worth a lot, odds are no one else will see it that way.