Tie-Downs
To transport your kayak, you'll need some way of securing it, whether on a roof rack, truck bed, or trailer. I recommend the type of tie-down strap shown above, with hooks on the ends, and cam buckles, not ratchets. Ratchets are a pain in the ass, and you don't need all that much force anyway. In fact, you don't want too much force, your boat is only made of plastic!
When it comes to tie-downs, more is better. On the truck rack, I use four per boat - two to secure it fore-and-aft, and two to secure it side-to-side. If you're good at puzzles, you could figure out how to do it all with just two, but I don't like to think that hard, and tie-downs like this are cheap. In the truck bed, two would do, but I have four, so I use them all. Especially on the highway with high wind loads, you will never regret using extra tie-downs.
Your tie-downs should be at least as long as your boat, so you can reach from anywhere to anywhere else, or have plenty of length to wrap around things. Light-duty tie-downs are perfectly adequate - you're not trying to crush your boat or pull the handles off !!! An inexpensive set of four should run you under $20.
Don't forget to secure the paddle as well, and the seatback. And don't trust the bungie cords to hold your PFD in place at 70 miles an hour!