Currently running a Garmin GPSmap 178c and am tired of the dreaded flashing depth while in PWS. Looking to upgrade but don't want to spend $5k to do it. Anyone running something affordable that they absolutly love? I want to be able to find depth in 600' of water and have good sonar picture for finding fish. Mine seems to just not being doing what I want. Can I upgrade transducers or what unit to purchase?