Hello !
I always wondered if its just me, or more people have that "spare part" bug. I mean:
Everytime I buy a bass or a normal guitar, and I'm up for some changes, I never throw away the old parts. I already managed to have a small collection of used parts, from old guitars, like a strat pearl pickguard (changed for tortoise), I'll now use as a template for making custom strat pickguards. Sometimes the included parts werent bad, I just had some other concept for the bass - like my Defil Lotos, with installed Hofner pickup. I replaced it, because I wanted to make something more like a P-bass.
Everytime someone has some old junk, that doesnt need anymore, I always say "I'll keep it man". Last time I got some electronics, and a set of tuners, exactly same as there:

The thing was, that one of them turned crooked, and it was unable to roll, but I think I can repair that. And thats is a good news for me, because even chinese made tuners are expensive here (at least 20$ for used ones). I also get a nice bridge, from the same bass, I'll also install in Lotos.
At least I just like to follow the auction portals (like ebay), to seek for some spare parts. For example I managed to buy a nice oldschool bass single coil, just for approx 10$, and a single tuner just for approx 1$, while new one costs approx 6$. It may not look like big prices, but for now I cant afford buying expensive stuff, because I'm unemployed, and dont want to take down my hobby. Also it may seem ridiculous, to buy one bass tuner, but to me its better to have one, than none - a month ago my friend needed a tuner, because one of his got crushed, and so it was perfect - he could spend rest of his money for a beer.
I also believe that one day, I'll have that much spare parts to make a bass guitar, just using them. I'll surely like this bass much, because I'm trying not to spend much on them.
So, I'd say that every spare part will have some usage. Thats why I never understand people who just throw away old parts, because they dont need them anymore (and I dont mean those, who wants to sell them later of course). Anyone with similiar bug ?