As mentioned, most larger machines are 220 3-phase. Generally not something residential areas have, so be prepared to either get some wiring done or buy a phase converter for the dryer plug in the garage. Or wire one in.
But, yes, some really good equipment can be found on craigslist. You can find a great mill for $3k or under, but the mill will be at most only half the cost. Then you have to buy a
good drill chuck that you
will not use as an end mill holder, holders or collets that you will, a good machining vice, a kit of hold down clamps, probably a rotary table and the chuck and/or clamps for that, dozens or even hundreds of end mills in both flat and ball-end, reamers in dozens of different sizes, countersinks, deburring tools, threadcutting taps, and specialty tools like slitting saws and cutters for slots, chamfers, dovetails, and so on.
And that's not even including the costs of calipers, micrometers, other layout tools, or the materials.
Or that a lathe is as useful, if not more so, than a mill.
Thankfully, all you need to start is a pair of calipers, a vice or clamps, the drill chuck, a couple collets or end mill holders, and a few of the cutters themselves. The rest will be spread out to buy tools as the need arises.
Has someone guessed what my weekend hobby is yet?
And, no, you can't learn machining just by watching videos. You learn it by watching
lots of videos, and reading
lots of books, magazines, and websites, and looking at
lots of other people's work, and making
lots of chips and
lots of mistakes, many of which you will only notice once the part is finished or while attempting to fit it to something else.
There is
nothing more aggravating than finishing a part, making the last crucial slot or hole that will mount it to the other parts, and
then having it slip in the vice, or turning around and whacking a dial and setting the cutter off at an angle.
Anyway. It's still the most rewarding hobby I've ever tried. Just be prepared to read a lot before buying anything.
Oh, and you
are going to have to buy a pallet jack, engine hoist, or other heavy lifting equipment just to get it set up, and rent a U-haul to pick something up, unless you have a decent truck. My 'light duty benchtop' lathe weighs upwards of 600 pounds, and it's on the lightweight side and doesn't have the base and other 'inactive' material a freestanding mill does.