If you have money and little time and patience, Bambu labs p1 or x1 series is one of the easiest to set up out of the box, and you can get or add on the AMS (automatic material system) which makes it easier to do multicolor printing. (US $700+)
If you have little money and more time and patience, Creality Enders are a good basic introduction to all the nuances, pains and heartaches of 3d printing but will give you a better idea of fundamentals. ($100-300) Expect to lay out another $100 for filament, upgraded bed and other small parts like bed springs.
Don't buy a used machine as a starter because you'll just be taking on someone else's headache, but once experienced you can find some craigslist and offerup deals for spare parts or a small print farm, occasional like new "used twice" $50 printers.
You've got a few answers from other people now. From my perspective, I'd say that the landscape has changed a bit since I started, at the time, the budget entrypoint was an Ender 3 v2 from Creality. Nowadays, they have better models, and there are plenty of other options out there.
I'd still personally recommend something like the (new) Ender 3, or similar, not because it's a great printer, but because the community around it is huge; you'll be able to get lots of help, and there are plenty of mods. Have a poke around Reddit etc and see what the most popular model is these days.
After a couple of years I heavily modified the E3v2, to the point nothing but the frame remains, and then I build a Voron v2.4 (350mm).
Once I had a printer, I started learning to design/model things, learn how modeling for 3D printing is different to other forms of manufacturing, and then just make things you want/need.
3D printing is still a hobby for me, that's the way I'd like it to stay so I've got no advice on making things for sale etc.
I advise against self-assembly. Especially for your first one, let the factory assemble it. Doing it yourself significantly increases the likelihood of alignment/calibration problems.
These will be frustrating and hard to chase down, especially if you don’t have a mechanical background. You can make a whole hobby out of building, modifying and upgrading 3d printers… but that’s a very different thing from using a 3d printer as a tool for other projects.
if you don't want the printing rather than tinkering with the printer to be your hobby, I'd go with Bambu labs. they're more expensive but they are absolutely unmatched when it comes to the out of the box experience.
I avoided buying a printer for years and years because I wanted to print things, not spend my time tuning and tweaking the printer. finally broke down last year and bought a Bambu P1S with the AMS for multi-material printing and it's been a revelation.
It's truly set and forget. Keep the filament dry, keep up with routine maintenance and you'll never have to worry about a failed print.
If you have the option near you, definitely search for and visit a makerspace near you. One reason is that 3D printers require frequent maintenance - something which will be "taken care of" at a makerspace - and you can spend time talking to 3D experts before making the commitment.
