Found one on ebay UK if you're on a budget:
LOW Seat Rail Subaru Legacy BD5 BG5 Impreza WRX GF8 GC8
Super low driverside seatrail for full bucket seat - Fits Legacy BD BC BG BF and Impreza GC GF
£94 shipped from the UK which is roughly $150 AUD. Apparently it's super awesome JDM spec so I assume it's RHD fitment.
