I know I'm probably a little late to put my say in, but i would suggest that if you are serious about persuing puppetry as a hobby or possible job, then you buy a reasonably decent puppet to get you started, i mean i know that people have suggested buying a cheap puppet, but unfortunately this might not help you in the long run.
Having a reasonably decent puppet to work with will help you to develop your skills as a puppeteer, but don't worry, this doesn't have to be an expensive puppet, just one that will function how you realistically need it to, meaning having a puppet with good flexibility and movement that appeals to you. For example, a fabric neck that is attached to the base of the puppet, rather than the shoulders will allow for better movement, also a puppet with rod arms that are either removable from the inside of the hand or are permanently attached will give you better control over the puppets arms movement, allowing you to manipulate the puppet more easily, etc..... i don't mean to over complicate things, because at the end of the day, once you have reasonable skills in puppetry, you will be able to make anything come to life, and i mean anything!! but i have been running puppetry workshops for almost 6 years now and believe me, if you are serious, then you will need good tools to work with to enable you to get a good start in puppetry rather than having to struggle using a puppet that does not move well and gives you painful cramp in your hand!!
OK, I'm not trying to freak you out, its really easy to be honest, i just want you to have the best start that you can, and maybe this means making a simple puppet yourself, check out pasha romanowski's
www.projectpuppet.com and take a gander at the 'glorified sock puppet' pattern, its not only cheap, but is an amazing base to build a really easy, simple, but effective puppet that wont cost the earth, but will give you a great start and the satisfaction of building your own puppet, but as the others have already said, there are people on this forum that make puppets like myself to sell and don't forget that between the lot of us, we have literally hundreds of years of experience and knowledge, so we are here to answer any questions you may have!!
have fun,
Ben.