The expected cost for an "average" ticket is $100 one-way.  There are expected to be standard tickets for $80 or $85, and Premium Seats for $100+.  Just remember that you will have to find your own transportation from OIA to WDW.  And if you are looking to use this as a means to access Port Canaveral - there will not be a station anywhere near the port.  THe OIA station is the closest one.  This is a high-speed train with speeds up to 125 mph, though the train will be unable to maintain this speed in many areas where there are low-level street crossings.  The trip from OIA to Miami is likely to be about 3 1/2 hours including stops at the other sourthern stations.