The $10 boards at the grocery store and beach shops are made for little kids and you will probably find them much too small and fragile for kiting.
As for the $200 boards, I've seen guys wo are really good at it run and drop them on the shore wash on a steep beach, ride the shore wash out 50-60 feet, catch a wave and ride it back in to the beach. Those boards are also the ones that can be good for kiting.
I'll have to give the skim board a try. I've heard of folks using skim boards but haven't tried one myself. I've thought about grabbing one of the cheap ones from local store and give it a go just for grins. At $20 it would be worth it just for the lols. What I don't understand are the skim boards that are $200+ in the surf shops. What exactly are folks using these boards for? I've only ever seen them used by kids to throw in front of them as they jump on and ride for like 5 feet.