Second Hand Professional Camcorder For Electronics Experts Only! Where Can I Buy A Cheap Second Possibly Third Hand Professional Camcorder From?

Where can I buy a cheap second possibly third hand Professional camcorder from? - second hand professional camcorder for electronics experts only!

I do not have much money, but desperately need professional video camera for a low-budget film, which I am now. It must be of good quality and possibly also in HD, but everyone knows where I can buy really cheap? I do not care if the second, third or fourth hand, I have only one now!