At my old house, I had dug up some PVC sprinkler lines to add my raised bed. So I cut the pipes, drilled small holes into them every 6" - 12", alternating sides, and connected them with 10 cent fittings from Lowes. At my new house, I built a similar system. The hard part was getting the connection from the hose to the PVC. They make adapters, you just have to find the right ones. This was a lot cheaper than the kits you can get. The kits aren't expensive, but I'm cheap.
I ran the pipes the length of the bed, and spaced them about 10" apart. The good thing with PVC is that it cuts easily, and you can adjust the lengths and spacings for whatever plants you have. I drilled 1/16" holes, 'cause that was the smallest drill bit I had. They work fine, but occasionally plug up; I just rinse out the lines every now and then.
I have a timer for each bed, and I run it for about 15 minutes each bed, every day, or every other day depending on weather and plants.