This is a video of the famous Disco, a budgie that has a large repertoire of words and phrases. Male budgies are mentally 'wired' to learn the dialect of the female they are wooing as part of their courtship so lone ones can learn to talk very well - but, of course, a single budgie is not a happy budgie so there is always an 'exchange': the owner benefits from the entertainment a talking budgie gives BUT the other side of the coin is the diminished quality of life for the bird itself. Disco has lived his entire life with three adult humans. Personally, I would much rather have happy budgies than a talking one - but that's me.
http://www.fuzzysnail.com/disco-talks/