Funny story for you all. I know a chicky that works at autobarn and about once a week some dickhead will come in and ask for a BOV, naturally she asks is the car superchard or turbocharged, the customer replies with, ummm ntiher its my stock V6 commador i just want it to have the cool "pschhh" sound
Over on another aussie forum a guy ran a BOV on his nissan cefiro to vent the boost created by his ram intake. Not only proved that ram intake is a load of ###### but made himself look stupid
Now, a BOV is used to vent boost pressure between gear changes so that when the throttlebody rapidly closes the air dosnt get forced back into the turbohousing creating big problmes that ultimatly will result in you turbo becmong a paperweight. NO TURBO, NO BOV
Now to answer your original question any auto stores in australia such as supercheap, autobarn, repco will sell BOV's, but rember ones that vent the gages to atmosphere and make a noise are illegal and are a defect. The only legal ones are ones where the gas is plumbed back into the exhaust stream as to comply with EPA emmisiion laws