I replaced the 20gb HDD in my iMac G3 I got a bit ago with a 64gb SSD, and also just swapped the RAM from 256mb to 1gb total so it's real fast now
I'll need to either replace or repair the optical drive that's in it, since it just spits out CDs, but for now I'm fine with just mounting ISOs. SNES games look super nice emulated on the CRT
The last couple months I also spent tricking out a Dell Poweredge R710 server, had to basically get everything for it (new motherboard, PSUs, RAM, HDDs, CPUs, fans, RAID card, etc). After around $400 total spent, it's got all 5 chassis fans, 2x Xeon X5680s, 96gb of RAM, 4x 2TB SAS drives, 2x 870w PSUs, and a GTX 750 Ti haphazardly shoved into the case in a very awkward way. It's currently running Proxmox which is hosting 3 main VMs, one Windows 10 VM I'm using to monitor/record my security cams (and for any other Windows things I may need), a Linux Mint VM that's used for work, and then for shits and giggles I setup an OS X High Sierra VM because it tickles me to have all three major consumer OS's running on one box at the same time (that's what the 750 Ti is for, passing that through so I have hardware acceleration in OS X
).
Dunno if this counts technically for this thread, but I replaced the breaks in my BMW X3 last week, too