Fish finders come in all kinds of shapes and sizes, but the only ones that are ever going to end up being good for you would be the ones that are really good at what they do. There is a pretty good chance that you will be able to find a number of fish finders that would seem almost ridiculously cheap by any standards at all, and the thing that you need to know about them is that they often tend to be terrible in a lot of different ways.
This is because of the fact that they have not been made with the highest quality materials at all, but much on the contrary would be the byproduct of something or the other that would not hold up to the rigors of real world use to any extent at all. When you opt for sonar for fishing, you need to ensure that you don’t get anything cheap, and the truth of the situation is that the more expensive ones actually have a pretty good reason for being expensive which is that they have been precision engineered with some of the finest materials most of which you are not going to be able to find anywhere else at all.
The fact of the matter is that there are brands out there that might sell their fish finders at an absolutely ridiculous markup, and you would not be faulted for trying to avoid them as much as possible. After all, what you are after is some kind of quality product, not a gimmick that would not give you anything meaningful to work with at the end of the day.