Sounds like you're talking about a ducted system if you're referring to a 10k install. The split systems only cost $800 to a couple of grand (depending on room size).
Some people buy around Dalkeith/Peppy grove/nedlands for the 'prestige' with no financial sense.
A friend purchased an 'investment' in the area for around $2m 5 years ago. Would be lucky to only lose 10% on the purchase. Upgraded to new ppor in mid-$2m. I can't see him getting his money back...