Hi Everybody (especially Scott and Mark from work who gave valuable advice, thanks guys!)
I just got a "greenewheels" electric bike from ebay Australia... mainly as it was inexpensive and seemed good, and as someone who hasn't ridden a pushbike much for a few years I didn't want a project, just a fun way to commute now that I have moved closer in to work.
Anyway the bike appears to use the same basic frame as the wisper 905, but kitted out a bit differently, and presumably a weaker motor to fit the road legal 200W Australian limit:
I haven't ridden it much yet (just on my 2nd charge of the battery now!) - but so far so good.
More indepth info in my little blog article I have constructed here: http://blog2.zog.net.au/category/electric-bikes/greenewheels/