I quite often browse used sewing machine listings on ebay, and then get overwhelmed trying to work out which might be an improvement to my current machine
The conversation prompted me to search again for one of the models I've been looking for, and what's made me happy today is that I found a very good one for £40. Thank you all for talking about it!
It's a 100-year-old Jones tailors' machine, with a vibrating shuttle and a harp space big enough to get an Alsatian through. I had the use of one in the 1970s, and they'll punch their way through layers of denim, sailcloth, and so on. I don't often use modern machines because so much of my work's heavy or bulky, and they either won't sew it at all or the plastic gears burn out.
If you tell me what you use it for,
@IanMcPhee, I might be able to make some suggestions?
Briefly, if you're doing straight stitching on heavier fabrics, it's hard to improve on pre-WWII machines. They only do one thing, but they do it brilliantly. Tailors' machines will tackle anything from a tent to a silk scarf. Many old hand-crank and treadle models have been converted to electric, but for smallish jobs, a hand-crank may be fine. Despite ME, I used to make nearly all my own clothes using a hand-cranked Singer 48K.
If you need an electric because you're sewing long seams or you know your arm won't cope with cranking, a converted old straight stitcher like a Singer 66K might be good—there are plenty about. If you need zigzag and so on, a domestic electric machine made before the mid-70s is likely to have decent gears and will cope with moderate fabric. Unless it's sold as refurbished by an engineer, assume anything secondhand will need servicing.
If you're only using light fabrics and sewing occasionally, there are dozens of options. Just look for something that's already been serviced, PAT tested, and has its tools. You sometimes get better value from an independent than eBay—if you see something you like the sound of, it's worth Googling it as well. In some cases you might even find the same small company offering lower prices for direct sales.