Does anybody have any knowledge about metal detectors.. I am in the market to purchase one that w?

You need to be more specific than that. A gold detector is extremely sensitive and quite useless for any other metal because it beeps for every little thing. What you want is probably a discriminator, or what they call a "coin shooter". That will respond only to coins weighing several grams within a few inches of the surface, and it will give some guess about what metal it senses. Some detectors pick up larger bits of metal several feet down. So you need to decide what exactly you are looking for, and then go ask a dealer what to get for that purpose. The more expensive models are much better than the cheap ones. Buy the best you can.