Do a search for "depthfinder" and "gps" on the board - lotsa stuff on these topics this past year.

Me? I use a Humminbird with sidescan for a depth sounder - cheap and reliable, you can get one for $150 on sale. And a hand-held Garmin Map76 is $300 and the most amazing GPS unit there is, with a base map and automatic track feature you don't even need to worry about waypoints - it shows where you are on the water in relation to landforms and navigation aids, and it lays down the exact route you followed getting there, so when the fog rolls in you just backtrack. Handhelds are nice for when it is dark, wet, and foggy, just stick it in your face when you need it and in your pocket when you don't. Real cool