Humminbird 718 or 581i fishfinder?

Ive been fishing blind on my t13 for a while now and im sick of it. I originally wanted the 385ci map and color sonar but just cant afford it right now. I really want a map/sonar combo to save all of my hotspots/rockpiles etc. And the color for picking up fish and structure better than a normal gray and black graph. Im seeing some super sweet deals right now on ebay and need some help. The 718 is a hi res. and has 320x320 res., with 2400w peak to peak power and is gps compatibile after u buy the gps reciever(additonal $100). The 581i is a map/sonar combo and comes with 640x 320 res., 2000w peak to peak, and already has an internal gps. I like already built-in gps on the 581i but it only has 2000w of power. I did want a min. of 2400w of power. The 718 is going for $178 and the 581i for $244, both with free shipping. What do you guys think? Which one sounds more with it? Need to asap cause im afraid these deals wont last long.

Ricci,
Been a while for this post but just wondering which direction you opted to: 718, 581i, or maybe the 385ci.
I've been looking myself and undecided which way to go.
Update will be appreciated.
Thanks.
superd/Danny