Can these power tools be reasonably easily bought used?

If you could test drive them, I would say yes (I would do so myself).
Of course you’d have to know what to look (out) for.
In bandsaws I can imagine that the axles and the horsepower are important (maybe it’s nice if the table is adjustable, and the fence is 90 degrees to it, or can be adjusted to be).
The saw itself can be bought new, that shouldn’t have to be a deal breaker.

For the drill press, check to see whether the colom is straight and sturdy.
What sizes the chuck accepts, and if it works good.
Is the engine speed easily adjustable (belts or electronic)
And again, the table, is it straight to the chuck and the colom, can it be tilted, and does it maybe have slots for accessories (same goes for the bandsaw).

I’m no expert.
There are possibly more things to consider.

I don’t know about easily but yeah you sure can find them used, one way put an add on Craigs list.
I bought a Craftsman 3/8s drill press in really good shape at a Garage sale for $25 so make sure to hit any of those as well.
I bought a brand new heat gun at a yard sale for $5
also remember anything like Craftsman or Snap-on buy them broken at a yard sale they have a life time warranty.

Well, I do build instruments myself: guitars, amplifiers, pickups, pedals etc… Yes you can always find stuff used. Estate sales around here are one of the best places to find good woodworking tools. I’m not the best wood worker but I can build a good electric guitar without much effort. I don’t have either of those tools to be honest.

Estate sales, auctions, garage sales, Facebook buy sell trade.

And that ain’t all you’re gonna need. In fact you probably require an apprenticeship.

I have found excellent prices on hardware at estate auctions, especially if you have the patience to wait through one in the rain.

There is always a way to get what you want at less expense, problem most people don’t want the wait or work involved.
Another way is keep an eye for close out sales.

You don’t need an apprenticeship, just practice. A lot of practice. You’ll make half your tools, what is on the market is either inadequate or too expensive. Take a look here if you want to geek out.

I have bought some tools at garage sales before. Facebook Marketplace or Craigslist are other options.