Questions about getting into growing wheat grass and juicers.?

So I want to start growing wheat grass and maybe barley grass, but I've never had a garden or much growing experience. If anyone could recommend a good site to buy the seeds from or give me any grow tips that would be sweet. Also I want to get a juicer, I'm thinking an electric one, does anyone have any suggestions. I am leaning towards an Omega j8300. Also I've heard that the nutritional content of the juice will be better if I let the grass grow for a while longer, any truth to that?