Lynn,
If you want to invest, I would go with "A". Instead of investing, there are some message boards relating to metal detecting. You could post your needs and I'm sure you'll get a few replies. Most guys are looking for "virgin" ground to hunt and if it has history all the better. I guess you need to think about what they might find. There may be some stuff with some value. You might let them keep everything they find for taking the time and it helps to offset the cost of the gear, gas, etc. If I was close by I'd grab my Whites XLT, come over and hunt it for you. Here's a few board links:
http://metaldetectingforum.com/
http://www.findmall.com/
http://forums.whiteselectronics.com/forum.php
Show us pics of what comes out of the ground!