Fish finder for older model xfactor

[Irishman]

So am looking to get into a fish finder. My setup is self contained bait tank and battery at the rear of the kayak. I like having extra rod holders on the bait tank. It's the older model xfactor, does not have the scupper holes / placement for transducer or intake for bait tank. So am looking for a fish finder. My focus on gear is function over form....I don't have a huge budget but can promise good karma. Ideally something reliable and tranfearrable as mechanically I'm not the best.