Make your own Dave, easy as and cheaper. Everything you need you can get from ship chandlery shops, there used to be a good one ( Nautical Supplies ) down near the Frances Bay duck pond !
Check Bunnings too Dave (if close by). They used to have adjustable bungees cords there that can be easily adapted to detecting. Heaps cheaper too from memory.
I just purchased 2mtr of 5mm bungee cord for $4.80 and 20 clips for $2.80. ( I did not want 20 clips, thats just how they come)
So... 2 bungee's for $7.60.