1. how old? Fixing the old machines can cost an arm and a leg.
2. what kind of experience do you have with CNC available to you at the shop
3. what are you wanting to make on the machine some are better for one thing than another and it's best to get the right machine to start with
4. What are the specs on the machine they can vary greatly on most machines based on options
About Hurcos the machines are good. Nothing wrong with an old Hurco quality wise. Also CNC machines last almost forever if taken care of and most are taken care of. I have an 1983 MB1. If they hadn't hit a cover and broken a servo, and I wasn't have weird bugs most likely due to to much time sitting it would be a great machine.
Now the Hurco is not perfect for me it was just the first one I found at the right price. The spindle is slower and weaker than I would like making jobs take longer. It didn't have coolant or an enclosure, which can hurt tool life and slow production down more. On the bright side a Hurco is a great machine for a beginner in a lot of ways. They don't need a CAD/CAM system to be easily used because they have a good conversational system saving on initial setup.
A couple quick pieces of advice buying used CNC machines don't buy without seeing under power if you can't fix it (and even then it's a bad idea trust me I know). If there are problems be afraid, fixing problems can be very difficult and expensive. If it uses tapes I wouldn't buy it.The first thing you would need to do on a tape machine is a controller upgrade. Look at the taper size and type CAT 30 is very difficult to find tooling for. I recommend a 40 taper. Buying an working in production machine is best.
I was able to get a Bridgeport Interact 316 for works out to be ~$8500 in Canadian dollars. With spare and some tooling The machine is in excellent condition for its age (1990) very little backlash (I need better tools to measure it) so the deals on old machines are out there if you watch, and the old CNC machine last. So what you want to do is very possible if you're careful.
The spindle noise can vary largely depending on speed and microphone quality so a recording is a bad way to tell bearing condition. The only way to know is to hear it in person.