Personally, I would not buy anything from Fitzeralds. I think his stuff is highly questionable.(that is a nice way of saying that he sells crap).
Do not believe me, then find someone that has tried his devices before. You can often buy his stuff used for one tenth of what it cost.
Now he will tell you it is because you need to be in the area of a real treasure. BS, one of my friends had one in Peru a few years ago. We pointed it at one of the largest gold deposits known in Peru. It gave a indication, in the opposite direction. So we took it where they make the gold into bars. No reading at all.
Be careful of people who pray on greed.
Want neat toys. Look at what Geologists and Archaeologist use. Look at what law enforcement use and look at what professional treasure hunters use. (Metal detectors, GPR, Inferred, etc.)
If the USGS uses it it is worth looking into.