Which is the best Key Finder item avail in New Zealand?

[Polio]

I have read briefly that there are apps available out there for finding your keys that work through bluetooth attached to a key-tag type product. You buy the tags and attach to whichever items you want. I always lose my 'keyless entry' car key-card so I'm really desperate to get hold of some of these products to use. I just called New Zealand's auth'd dealer of Apple products and they said they don't have any of the key tags for sale. WTF! Surely this is a basic necessity. If a blimmin portable phone base at home can make the handset you've lost in the house beep, surely there is something 'new generation' that I can use with my iphone and keys?! Can anyone tell me which is the best app that ties to the best product and where I can order these from in little ole NZ?