Depth Finders

I have a limited budget so I am trying to think of a way to put the right combination of fish finders and GPS on my boat without spending more than I need. What I think would work the best for me would be a great quality GPS, but not necessarily a great fishfinder unit by the steering console. And then put my great quality fishfinder unit without GPS up front by trolling motor. Does this make sense for my situation? If so, which units might fulfil this set-up the best. Who makes a great GPS unit with a mediocre fishfinder? And what is the best fishfinder without GPS? Thanx for your help!