Don't dumpster dive, go to a pawn shop or buy the tool your mechanic wants to sell off cheap. My mechanic friends go to 'estate sales'/garage sales in upscale neighborhoods and consistently picks up the set of SnapOns or decent DeWalt power tool for pennies on the dollar because some rich bro wanted to tell his friends about how he only buys 'the best' and only used it once. One pal grabbed a ~15 year old Milwaukee reciprocating saw for us$20 a while back...it looked like the prev owner never even opened the case.
OTOH...I guess that's really just trading the tool restoration hobby with the cruising yard sales for deals hobby.
Estate sales take a lot of time. Occasionally you'll find a treasure trove, but more often than not, they're just selling a dead person's junk. The best source of tools I've recently found was a local machine shop going out of business. I chatted briefly with the owner, who was retiring, and he could not find anyone else willing to learn the business/invest/take over. So he sold everything in his shop. Lots of good stuff.
Congrats on the score (why don't I ever stumble on those), but I suspect the ratio of 'yard sales with good stuff' to 'retiring from machine shop and everything must go cheap' is pretty skewed.
OTOH...I guess that's really just trading the tool restoration hobby with the cruising yard sales for deals hobby.