Smart people never buy a box with tools already in it.
Actually I think that's the best way to buy tools as far as value goes.
I see pretty good deals on tool sets on Craigslist fairly often, but still about 4 over priced to one good though.
One thing people who sell a lot of tools agree on is that you should break up big collections into sets/items if you want to make more money from the sale.
I believe this is true - given what I see on the more realistically priced sets that actually sell.
Obviously then you will get a better deal by buying the whole collection.
The key is knowing what you are looking at.
I have bought a couple of full boxes off CL in the past few years in the $500 range. Each of them had specialty tools I needed worth well more than what I paid for the lot.
The main issue I see it that by the time you need a big tool set, and know what to do with it, and know what its worth, you already own the majority of the tools so its no longer worth buying a collection.
Some exceptions of course, like my recent situation. I've gone from general mechanic work of whatever job on whatever vehicle except rebuilding transmissions, to now mainly just building transmissions.
I also just bought an old wood frame pier and beam home. It needs a fair amount of work, and the prices they want around here are astronomical for no bigger than the jobs I need done are, some of which I had to go back and fix right anyway.
I used to do construction/carpentry 30-35 years ago for a living, so I'm going to just do it myself.
But, I don't have (or didn't anyway) much in the way of carpentry tools. and the cost of those is one of the things that put me off just doing it myself in the first place.
I looked on CL for deals, but didn't see many worth pursuing. Did buy a couple of things there, and still look daily for stuff I will need later on, but mainly I had to go buy new.
Now just last week or so I saw a new ad posted. Guy was selling a big collection of tools, 2 circular saws, miter box, drills, small compressor, air line, 100ft ext cord, sawhorses, multisaw, dremel, bits, blades, ladders, paint tools, drywall tools, kneepads, hammers, full belt, wheelbarrow, small concrete tools, air nailers, squares, and quite a lot I don't recall right off hand - all for $500 obo.
Having recently bought most of that, I can tell you it was a lot more than $500.
