As of today Remote Control Systems (RCS) is now able to offer the well known BIK series installation kits for a much lower price.
The # BIK-U3a and # BIK-U3b will be A$27
The # BIK-U6a and # BIK-U6b will be A$29
Likewise the well known RCS # RELAY-1 will be A$27.
Beware of the inferior and more expensive copies now on the market with the same part numbers.