Japan or Singapore would be your best bet. The Aussie dealer was bullshitting you as the SiR was never released here - most don't know the SiR exists until I drive into their lot
Mine's the only one imported into Australia before our laws changed other than a CRX EF8 SiR in Queensland. They won't even get the parts in for me as the car wasn't purchased through Honda Australia (pack of wankers).
New Zealand would be a better bet as they have very loose import laws and there are some SiRs there - but again they are imports, not dealer supported. They can also get stuff through Honda Japan.