I got a set of four
Urko clamps from Tilgear when they were on offer. They're 300mm with roughly 80-100mm throat, and I really like them.
They're like
these, except that they're simpler and have wooden grip handles rather than T-bars, which I much prefer for most things.
10 quid + VAT each - not the cheapest, but they grip well and I find them very handy. The only thing that stops me getting more is that Tilgear have stopped importing the handled versions, which are brill.
The shafts and general design, incidentally, are very similar size to the Festool-style plunge saw rail clamps, so much so that I did wonder if Urko OEM'ed to Festool.
Those rail clamps, from a range of people might be a good idea, as they're under 10 each (or recently have been!). You could easily make a "foot," to slip over the straight end, and they have the huge advantage that they will fit into 20mm MFT and "Workmate" dog holes. I have a pair, and will get some more after I buy an MFT top (keen on the Axminster one presently).
These Axminster clamps will also fit MFT, etc., holes:
and I use them that way quite often (in a portable bench). You can also join them end-to-end (with a bit of ingenuity), to get double-distance. Their big drawback though is that they do slip - I have yet to find an effective maintenance/cleaning process.
I mention them because they were on offer at around 10 quid each a while back. I think they're overpriced at 17+ each, but they're my goto clamps for general use. I should also add that RogerS really hates them as he had an incident where red dye came out of the pads onto a finished piece. I've had no such issue, but generally don't use them for posh stuff. They do get in the way a bit so you have to plan a bit better (the Urkos generally don't). They also tend to move things a bit as you tighten up - the jaws only come parallel after quite a lot of force is already applied. I've never come close to breaking them, but bending, certainly - I wouldn't contemplate thinner plastic ones for that reason. Rutlands do the same clamp, in green (or used to), but I no longer buy from them.
I do appreciate the costs: Both types are too expensive for me to buy more at the moment. Perhaps you can find some s/h...