Thanks for the replies.
I'm pleasantly surprised by the late surge of interest in this topic. A week ago, I'd almost given up on the thread, and was considering giving it a bump.
Since my original question, things have moved on a bit. I've bought a few black handled Suzo 500s from Ultimarc, and fortunately he appears to have plenty more in stock.
Also, by an amazing coincidence, there's a guy selling custom hollow Suzo 500 shafts in the Buy/Sell/Trade section, so I've ordered a few of those as well.
With regards to GroovyGameGear, I did notice some time ago that he still has a few blue Suzo 500s left in stock. However, they're only being sold with a fairly expensive mounting plate that I'm not really interested in. And I can't really justify spending almost $50, plus shipping across the Atlantic, plus possible import duty, just to get a different coloured handle. However, on further reflection, I've nothing to lose by sending him an email, so I might just do that.