Well, you are paying for a number of things. In my list of priorites, when I upgrade this winter, I will be paying for color, pixel count and screen size. If you are fishing in 50ft or less, you probably dont need to be concerned about power. For the money, I have decided to go with the new Eagle units. Take a look at some of the ones Wade has posted in this forum.
Garmins are great units, as are Lowrance and Raymarine. I am operating an Eagle purchased in 1996 that still works flawlessly. Would I have been happier if I had bought the equivalent unit in Lowrance or Garmin back then? Probably not. I am upgrading to color and a higher pixel count.
Good luck,
Dave