In the mean time I've managed to find a couple but there appear to be slim pickings. Any other suggestions apart from those below would still be appreciated.
I have a friend with a permanent hand injury which prevents him holding the usual type of spoke key (contorting the hand around the spoke etc). Nevertheless he's still keen on cycling and maintenance so I'm trying to help find him an easier to use tool.
I'm also interested from the perspective of using a twist-resist type device. It's a tool that isn't without its controversy but I'd like to see for myself if there is any benefit to be gained from using one. The way I see it, to have any benefit from using one you would need to hold the spoke as close to the nipple as possible. That kind of precludes the use of a standard (tall) spoke key.
I have seen the one which Peter suggests (thanks Peter) but the sizes indicated on that website suggest that all those Sunlite spanners are too big for the DT nipples (which are 3.2mm or 0.127"😉.
I have found one which I think would suit: The Cyclus Profi Spoke Key
It has the advantage of being a three cornered design too.
[IMG]cyclus-tools.eub89e8c80a7.jpgOpen ↗[/IMG]
Cyclus also has an agent in Australia so that should be doable.
It may be faster to use the Super B version (open ended) but i can't find an Aussie agent for them.
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Here is a cool custom made job used by a bike polo player (they have wheel-covers which also necessitate a low profile spoke key)

I was mulling over the reason for there being so few keys of this style for standard nipples and I guess it must come down to the extra (un-needed) leverage which a spanner gives you. The chances of stripping the flats off a nipple are increased with this type. However, if you need the lower profile, then you're out on a limb apparently.