Where 'older' vices are concerned, I think it depends on a couple of things Mike – will they fit and how much?
I have a couple of large good quality vices that I can only use on the Victoria HO – they'd be much too large for any of my other machines. Most "industrial" quality stuff was made for use on bigger machines and although it's tempting when you see this stuff, it's not much use if they won't fit on your kit. I have seen similar vices (Abwood) to my two go for £150+ each but I didn't pay anything like that, only about £20 from memory. So the asking price has to be considered in the equation.
I have a number of smaller vices, including a 'Myford' one – but the small one that I tend to use a lot, is a cheap chinese "push down" design that seems to be good enough for most of my needs and has long bolting slots. This means that it can be fixed to my various (all different) T-slot systems. I doubt I paid more than £20 for that new either (although it was 4-5 years ago now).
Thinking about it, I don't have any "medium" vices (except for my Atlas Shaper vice which really is worth it's weight in gold) as I guess I tend to clamp larger work directly to the milling table. A 'Kurt' would be very nice but would cost more than I've paid for most of my "old iron".
So industry (or s/h) quality tooling is certainly well worth having provided you can actually use it (e.g. it will fit your machines) and that you don't pay through the nose for it. I understand John's view by the way – but I've tended to purchase my workshop in small increments over the years. Although the total spent would add up to quite a bit, I've been able to afford it on that basis. Others might prefer to buy the best on day one and then manage to forget what it cost over time. Different horses for different courses I guess.
Regards,
IanT