(from Port Orleans) "Boat rentals are also available. Choose from kayaks, Sea Racers, the Boston Whaler, and the Sun Tracker. The rates are based on a 30 minute time period and they range from $6.93 for the kayak to $31.95 for the Sea Racer and $47.93 for the Boston Whaler or Sun Tracker. Rent a bicycle or Surrey bike to tour the riverside path to Port Orleans French Quarter or to help you make your way around the Riverside resort. Surrey bikes are $20.24 per 30 minutes of riding and the bicycles are $9.59 per 30 minutes of riding or rent one for the whole day for $19.17. "
You can also rent from the Fort Wilderness marina, and near Cap'n Jacks at Downtown Disney, but I couldn't get pricing info on these. I would imagine it's on par with PO.