Hey Hels... i go tour alarm from a company called CTC Communications... they have from what i researched and i did a lot of research...the best prices the one we are getting is hardwired but we are getting a friend to install it .. i would probably blow up our new house if i tried to do it
But there are many wireless alarms out there.. i highly recommend CTC (ctccommunications.com.au) to look at they have a great eshop online... they even matched a price i got on ebay for detectors...
hope this helps in some way...