There is no place you can buy a time machine. Steven Gibbs does not sell a time machine. He sells the Hyper Dimensional Resonator. It's a radionics machine that users experienced in astral projection, claim it produces an enhanced astral projection experience.
Well as of now, everything said about HDR is just a claim. Whether it's Gibbs saying "It's a time machine" or us saying "it's not". Nothing proven either way. During one of the interviews with Steven Gibbs on Coast to Coast AM (I think it's the one with Art Bell), some guy called in from Ohio and told Art that everything his guest (Gibbs) is claiming is BS and he's a fraud. Then he went on to claim that he himself had been doing research in the same area for 30 yrs but he was not at liberty to disclose anything. I think he even went on to say that just by calling the show, he had put himself in harm's way.
Another guy had called in once and said that he'd been working with a scientist in the similar field and their findings were similar to what Gibbs was describing. So, as I said, all claims but nothing concrete. And I personally don't think if there was eve a Time Traveler - he/she would share details online (no offense to John Titor).
As far as HDR goes, IMHO - astral yes. Rest we will never know