as stated.. older machines can very likely be better units.
singer is good, and you can get zillions of cool feet from them. teflon, roller, zipper.
if looking at a vintage singer, make sure it is a vertical shaft type, not a slant foot.
you should not really have to PAY for a sewing machine, at least, not hardly very much.
friends will be willing to give you one, if only so they can out from the guilt of having, but not using, theirs.
do internet research on how bobbin tension affects things, and the mystical bs surrounding it's adjustment.
oil and thoroughly clean the machine. do not ever lose sight of the hard fact that a sewing machine is a MACHINE.
they are not magic. not spritual. not hype. they are machines, and as such, will, if you dork with one long enough to develop an understanding of your opponent, will do what you are telling it to.
stitches. forward. backwards. zig-zag..... you're There. circa 1962, it's all you'll need.