I bought a used helix 7 chirp/gps/di last spring for $600, was a great purchase for me, I don’t think you’ll be disappointed with a helix 7. I really like using the down imaging when ice fishing, but it can drain your battery’s life quickly if you use gps a lot.
Make sure you have good battery power is something else to consider that hasn’t really been mentioned. When I go away camping for a few days and going portable I’m often running out of juice, (using a 12v 7a) I’m contemplating getting a Dakota lithium for a power source, but it is expensive