I've been thinking about purchasing one of these to use when I bank fish or when I take my little jon boat out to one of the smaller lakes in my area. Does anybody have one or know anybody who has one? I'm wondering about quality of these things. How accurate AND how durable. It looks like they range anywhere from $80-$100 which is too much for me to just take a chance on. Itd be really nice to finally see the bottom structure of these lakes though so if it's a good piece of equipment I'll spend the money.