Sue,
similar to the autobarn ones, Andrew at Board Crazy also has these ones for $99:
http://www.boardcrazy.ashop.com.au/p/980861/handirack.htmlI have a set (use for hire cars when travelling away) and they work quite well. The board tends to bob up and down on the roof a bit (as the racks have a bit of give in them) but you stop worrying about it after a while. The strap that ties around inside the car can also be a bit annoying if you put it too far forward and it rubs on the top of your head.

lucky you getting to sail during the week - thats where all the wind has been lately!
cheers
james