All I know, is my boyfriend spent about $1,200 a couple of years ago on a metal detector. I don't remember what brand it was though. Anyhow, he used it a few times, and it now sits in the basement unused, collecting dust and probably will rust away before he even thinks about using it again. On the other hand, I have a lot of fond memories from when I was little, my dad had a metal detector and I loved spending time with him using it. He used it pretty frequently. Never found much of value, usually just change and odd bits of metal. The quality time with him was worth more than anything he ever found though, I'll say that. Go on, get it for DH. He'll appreciate it.
Here is a link that may/may not be helpful. I am pretty sure this is where we got ours.