For what you are wanting I would say the Lowrance Elite-5 would be a good fit for you. You get sonar, down imaging, and GPS mapping on a 5" color screen for about $360, and I think that does come with the transducer. I am biased to the Lowrance units though. I just haven't found a better value for what you get. I like the 7" screen model because it is a widescreen (landscape instead of portrait) and just for the cost compared to the $1000 units I feel like I get all the same features without the cost. I especially love the down imaging!
http://www.starmarinedepot.com/lowra...m9sRoChOvw_wcB