Agent009,
There are definitely aftermarket roof rack systems available here in Aus but if you're only thinking of getting them to transport your kayak then maybe you should consider some kayak transporters. I've seen them i think at BCF and other outdoors stores but definitely at Anaconda. They're cheap, easy to install and remove and store away -
http://www.anaconda.com.au/Product/W...oft-Roof-Racks - these might be just what you're looking for.
As for the kids situation, sorry i can't offer a skerrick of advice on that one!
Mopud