Upgrading my fishfinder

[convergent]

I have an older Lowrance fishfinder that is mounted on a swivel so that I can see it when driving the boat, or spin it around and glance at it from the front fishing seat. I want to upgrade this unit, AND, I also would like to have two separate head units... one at the bow and one at the driver controls. The Lowrance has a transducer and a paddle-wheel mounted on the stern. I'm just trying to weigh my options here because I know they make networked units now. I'm not looking to spend a ton of money on this, and do mostly bass fishing in lakes that are no deeper than 30', but a GPS with topographical maps would be nice since I'm new to the area and their are many lakes to fish.

One option I have is to just get a new inexpensive unit to mount up on the bow and attach the transducer to the trolling motor. Another would be to buy a new more robust unit with GPS to replace the Lowrance, and then relocate the Lowrance to the bow. If I did that, I'm not sure the cable is long enough. Can these cables be spliced to make them longer, or is that not possible? Another option would be to buy two new independent units, or buy two networked units. From a money point of view, is it going to be cheaper to buy two units with separate transducers than getting into the networked units? Again, not looking to spend thousands of dollar here.