I have been using a Lowrance for quite a few years. My first unit was a combination Loran and Sonar and I currently have a combination GPS and Sonar. Both units have been great and on the rare times that I needed service on the old Loran/Sonar it was quick and done at no charge. Although the combo units are more expensive, they do have quite a few sonar models for $500 and under.
I think I shoot gave you a good tip. This is a very good unit at an excellent price. Although it is a discontinued unit from Lowrance it is a quality unit and I will buy one at that price. I was a die hard Humnmingbird user but had continuous problems with moisture in the screen and poor service on them. I've not had that problem with Lowrance.
If your into serious fishing and sounding??? Look no farther than RayMarine. They used to be Raytheon. They invented radar during WW II. There units are very hard to beat for the serious fisherman. Good Luck and break em all. Jeff
Have also had good luck with Lowrance, biggest problem with ALL electronics mfg. is they become obsolete after a few years and getting repairs (IF needed) are difficult to non existent. Fortunately I've never needed any on my Lowrance, but know that if or when repairs are needed I"ll be S-O-L due to age. Ross Puls