We are also staying at a WDW resort (Port Orleans Riverside) and will need to get back and forth to Universal for a couple of days. When are you going to be there?! We leave this Saturday and will be there through the 23rd!
The least expensive way would be to rent a car for the day. Its really easy to get to US/IOA from WDW. The next best option would be the Mears shuttle. I think its around $20/pp roundtrip.
We are also staying at a WDW resort (Port Orleans Riverside) and will need to get back and forth to Universal for a couple of days. When are you going to be there?! We leave this Saturday and will be there through the 23rd!