One does not simply need such a device...
I need a phone to talk to anyone outside of my home. I need a bicycle, car , train, or plane to visit anyone that not relatively close to me. I need a microscope to see very small things. I need a telescope to see far away objects.
There are times when we just do need a device or machine to accomplish something.
And, likewise, when it comes to time travel, I would think a device or machine of some sort would be needed to move, physically, in time. That is, if it can even be done at all.
Now, in reference to Steve's HDR device, he does claim the user can physically travel in time, past and future, with his unit, if all the instructions are followed on how to use it. He doesn't guarantee it, and there is no refund. I'm sure he sold many that didn't do a thing, yet, a few have come forward and said it worked for them.
Is it worth $360.00 USD to find out? That's up to each individual. The schematics can be found on the internet, and I think he sells the plans on his website. A three dial radionics device, powered, can be built for under $50.00, the HDR with that electromagnet probably would cost a little more, I assume.