I picked up a second-hand PMAX 170, greyscale finder last Spring. I hooked it up to 8 AAs per MPs design and it has worked like a charm. It's simple for me to operate and it locates fish and reads out the bottom depths/contours of the lake. It was on ebay and the guy who was selling it just happened to live in-state so the shipping was cheap. I could have done a lot worse for more money! ( I was originally looking for the Cuda 242  but couldn't find any for sale in my price range, i.e. "cheap") ;)