Fixing Auction Tools

Older name brand tools are usually worth the time to try to fix if you have the time.
At auction in my area, junk tools and unwanted hardware frequently come up.
I've ended up with a lot of stuff that doesn't work, but oftentimes the fix is relatively cheap ( if ya know how to source parts ).
One example from earlier this year was $5 for a four inch German made Metabo angle grinder that was beat up, and sounded like rice krispies when I plugged it in. Including shipping, new bearings cost me less than $8, and the couple hours I spend cleaning the grinder out was well worth the $95 I sold it for.
I've also bought large amounts of hardware at auction for really cheap. It doesn't seem like much, but it saves a lot of money in the long run especially with $1 box lots .