I know this is basic stuff, but all the options out there are confusing me. Color looks like the way to go I think, not sure about DI, maybe with the right choice I can add on as I get more cash. I have $500 maybe could scrape $600 together for new elctronics. I have an older GPS so I do not have to have a combo. Looking at the Hummingbird 596c HD and the 597 because of the Navionics feature and the newer GPS technology. Any suggestions thanks in advance.

I don't have any good feedback for the Birds (they seem nice). The Lowrance HDS 5 would be at the upper end of your price range. Leaves you open in the future for adding structure scan (side scan & down scan for $600) and also for networking multiple HDS units together.

If you are looking only at downscan, then no reason to go HDS. I'd get one of the dedicated down scan units in either Bird or Lowrance models.

You've already narrowed the field to the two units with the most bang for the buck in your price range. The 596c HD DI has more than just DI. It also has standard 2D sonar. The 597ci HD DI has memory slots, mapping, and 50 channel GPS and again the 2D sonar. This down imaging is good stuff for looking closer to the bottom than standard 2D. In fact the DI on these units is probably superior to DI on the Hbird or Lowrance high end units. There is one shortcoming to both these units which may be corrected in a future software update. The combo screen showing both the 2D and DI put these one over the other instead of side by side. Greg Walters at Hbird has put in a word to change this. But even if it don't get changed, you've already narrowed the field, in my opinion, to the two to choose from.