I see the add is gone now, but I would give an old Husqvarna a chance. I know the old 19 and 21 are prone to freeze up and need quite a bit of oiling to shift smoothly again. It's relatively common for these to be stuck in reverse or not zigzagging properly, it is all about tentative, repeated oiling. These are very nice machines when they are sorted out, and all gears are metal. Knobs and cams are plastic. It's not always easy to do more than clean up and minor repairs on these. I think the race and hook area requires special tools to be fully disassembled. The ones I worked on only needed cleaning, oiling, and new belts for the motor.
The later models I don't know much about. Some are easier to clean and sort out in the hook and bobbin case area. Unless there's something major, they often run fine after a cleaning and DIY service. You have to oil the gears, even if they are so called lubrication free. After 40 to 60 years, the sintered gears are in desperate need of new oil. The advantage with these are the stitch pattern cassettes, if you look for stretchy stitches it's hard to find all metal models among any brand. New belts can be a problem to find, at least the cleated ones. I guess these are the models LeilaMay warn you about, if gears crack, macine is missing driving belts, etc it cam be more that just a bit of work to have a fully working machine.
I once bought a non-working Elna Supermatic for about $40, all it needed was a lot of cleaning and oiling. It sewed fine when I got the correct bobbin, and ran even better when I replaced the friction wheel on the motor. Some times it's worth taking a chance; I got a machine with freearm zigzagger and stretchy stitches.