I would buy the best Hummingbird unit you can that is within your price range. If you are willing to spend $400 or $500 then that is what I would do. You will not regret it when you see that image on the screen. As stated earlier the CI HD models are nice. I have a 700 series CI HD with down imaging and I find all kinds of structure and fish in the water, now I just need to figure how to make them bite, LOL.