I suggest that you do your own homework. Check out PI instruments and Flux Gate technologies. If I find any treasures, I'd be nuts to tell everyone (read that the IRS) on the internet. I look into every aspect possible of the devices that I want to buy. I wouldn't depend on anyone else for a testimonial, since often they don't know how to use such new technologies. With the costs so high, you'd better know what you're doing, and be committed to learning all you can to work it. I think that if you try to do it on the cheap, then you'll be having trouble getting the job done. Prepare to pay 30 to 40 K for the necessary systems. With the AL instruments, don't limit your definition of 'treasures'.