If you have a fish finder that you want to add to your kayak, most tutorials will have you drill through the boat itself to attach. Now, I might be alone in this, but I don't want to do that. There's just no reason to do that or to use glue. Thankfully I came across this video which shows one method of using a fish finder on your kayak that doesn't involve drilling or glue! For this specific set up the Fish Finder was $200, the pelican box was $45, the battery was $20, the arm was another $15. Overall you should be able to spend right about $300 for the set up, in addition to the cost of the fish finder.