You can get a "mac layout" tenkey via one of the programmable ones, or by remappnig keys. If you really need the extra key, a tipro would do.
Why would it double the cost? Standard mechanical tenkeys aren't that expensive (even new ones) online, and even programmable ones from tipro or access get pretty low if you wait on a deal.
The range of mechanical keyboards in Australia seems more limited compared to overseas. The PC Case Gear
mechanical keyboards section is the most comprehensive list of mechanical keyboards I have found in any single Australian reseller, and they even have a mechanical keyboards section although they do lack any Matias keyboards.
PC Case Gear is also about 10 minutes from where I live, so pickup (saving on freight cost) is also a possibility.
About half the mechanical keyboards there are backlit, but there is only the one Mac layout keyboard, being the Razer BlackWindow Ultimate Mac Edition (which also happens to be backlit).
Is there a backlit programmable mechanical keyboard that anyone would particularly recommend? Is it under about $150 in price??
The Razer is $149. The Matias Tactile Pro 3 is also about $149 (but not backlit).
A third option might be a Mac layout backlit non-mechanical keyboard (shudder). My first aim was to get a backlit keyboard, but I have convinced myself that a mechanical keyboard would be better, and a backlit mechanical keyboard would be perfect, but the Razer seems to be the only one available.