The i-pilot isn't a trolling motor, it's an attachment. The i-pilot will work with 3 minn kota trolling motors...the Riptide, Terrova and PowerDrive 2. Be-aware of the two different types on i-pilots too, i-pilot and i-pilot link. The link allows you to connect your trolling motor to high end humminbirds.
I purchased the i-pilot off ebay for $320 new and a used Terrova from craigslist for $450. Best decision I've ever made for fishing!!!
The i-pilot is WONDERFUL! I use the i-pilot's SPOT LOCK feature, it truly takes away the hassle from trying to anchor. Also, I can use the AUTOPILOT feature to keep the boat heading in the same direction (great for trolling or setting the trolling motor into the wind with a low speed to slow down my drift).
I have a couple of videos on ipilot and plan on adding more:
http://www.youtube.com/user/AmericanAngling/videos?flow=grid&view=15