My very first vintage machine was/is a Necchi Supernova. She's a wonder of engineering! And my sewing machine guy raved on about the quality of her fitting and the substance of her. Honestly, I love her and blame her entirely for my obsession with vintage machines. I don't know about parts - she came to me intact with all accessories, including a full set of cams, multiple feet, extra bobbins, a ruffler, tools, and 2 manuals. So I haven't had to look for any. But there are Necchi groups out there, ought to be a resource.
That said... her decorative stitches are not very precise, and her straight stitch is just OK. (My Singer 500A sews much nicer.) It's possible these issues could be fixed and the Necchi would absolutely live up to its reputation. I took it to the shop when I bought it and had the guy there get her working again, but it was also the first time for him to work on a vintage Necchi and maybe it could still be tweaked a bit.
I also think I might just be a peasant at heart. My favorite machine right now is my little straight stitch Sewmor. Nothing fancy, but SOOO quiet, and makes a nice stitch.