My opinion. It's a kayak, get the cheapest available...especially if your hard on gear. You'll really only use it for depth and temp...remember you'll be limited my winds, power boat activity, etc. I use a atv/lawn battery fits in a milk crate, with the transducer attached...all 1 single piece if gear.
Like Ham siad, 9 out of 10 times I use my paddle or drop the line and pick it up to see how far it fell.