Looking For A Used Metal Detector

I'm in the market for a used metal detector. My current one is very entry level; I think it's a Bounty Hunter Gold Digger that I bought online from Goodwill. I also have a Bounty Hunter pinpointer that I bought new off Amazon. It might sound dumb, but if anyone knows how to open the battery compartment on that thing, that would be very much appreciated.

The Gold Digger is okay, but it's not very powerful, and it doesn't give off useful (digital) readings, like depth and tone. It's also not very accurate in terms of pinpointing where the object is, i.e. the circle thing is solid, not hollow like the more expensive ones. I did get my money's worth, though, when I used it to find a lost house key in the front yard.

Anyway, I'm looking to maybe spend $100 on a well-loved metal detector that's a little more advanced, just in time for the summer season. What would you recommend that's in that price range? The wife wants to get me out of the house, so maybe I can convince her to let me spend a little more than that. Any advice would be appreciated. Thank you in advance!