Metal Detectors

[Lynn]

Any of you knuckleheads know any thing about metal detectors. I need one, but am not going to become a metal hunter. We are landscaping our historic area property, and I have uncovered a boat load of stuff, such as:
Model A jack, a very worn horse shoe, huge set of leaf springs for a Model T (I think), multiple hardware parts for buggies and cars, and tons of bottles, mostly broken, from the 1800's to the 1970's.

Before we sod and lay concrete, I would like to go over the entire area.
Looking at these:

Choice A: http://oklahomacity.craigslist.org/ele/5082186397.html

Choice B: http://oklahomacity.craigslist.org/spo/5100575828.html

Anyone know ANYTHING about metal detectors. Choice A is local to me, the other about an hour away. A is more expensive, but if it will do a better job, I am OK with that.

Any opinions?