I got Thule racks and saddles for my Accord last year. They were expensive, but the peace of mind they offer was worth it. I used foam blocks and then a cheap crossbar kit for a year before investing in the Thule equipment. The foam blocks are quite secure, but there are a lot of contact points with the car where abrasion can be a problem. The cheap crossbars worked but the kayaks always wiggled around in the wind.

If I had roof gutters I would have built more solid crossbars and a set of custom saddles for each boat. I thought about putting custom saddles on the Thule crossbars, but decided that I wanted to spend more time kayaking and less time in the shop, so I bought the H2Go saddles and hit the road.