I've used both and they seem pretty similar. I would say for sure that Keyster are not worth 4X what K&L are, 4 kits for $56 sounds pretty good.
Personally I only use the gaskets, float valve, and the air/fuel screw/O-ring/spring/washer. Unless there's an obvious problem with the old jets or needle, I put them back in. Buying the kit and using just those parts is still cheaper than getting them from Honda.
Sometimes the needle and needle jet wear from contact and new ones are desirable but in general the jets just do not wear out, so using what worked on the bike before is a safer bet than installing something new. Probably K&L and Keyster can make a decent jet but I trust the originals from Keihin more.
