RE: Does anyone have the Hummingbird 525?
I'd really stay away from the Wal Mart sonar units. They are generally factory seconds (you really think wal mart is paying full price for them?), or repaired units from other companies. Best bet is to save a little more money, and buy a lowrance, garmin, or higher end humminbird. It'll hurt the wallet, but the pay off will be worth it.
In fact, I think I have a Garmin 160 and a 140 i have laying around I can sell for pretty cheap.