This has been debated over and over many times. If you add up what you get in that "kit", you will find that the same money will buy just about the same in certified new parts. I'm not saying the kit is bad, but if you are going to spend that kind of money, why not buy parts that are built to a certain standard, wether you are going to write experimental on the side of the plane or not? At least you have the option of going certified, and ending up with a plane that will be worth twice as much in the end. But if you have the 50-70K and want to fly a Cub, why not just buy one and fly?, instead of buying a pile of parts that will probably end up rusting away in your garage while you look at them and dream about flying. If you look around, you should be able to find a nice Cub for 40-50k, spend the rest on gas, fly, and be happy.
If you enjoy building, and have the skill and knowledge to do it right, by all means, get a pile of tubing and some drawings and build away. But building is almost never a way to get a cheap plane. If I was like don d and could somehow take a whole year off, (that will never happen, but what a wonderful thought), the last thing I would want to do with that year is work full time building a plane. I'd take that 30k, buy a old Cub and fly the hell out of it for that year instead. But building planes for me is a living (work), so I suppose my perspective is different.