I checked this out for our January '01 trip. Taxis even then were not cheap. I figured with taking taxi, I was spending more, not saving any $.
The cheapest way was taking a Lynx bus from the TTC and then taking the I-trolley to Belz.
Cheap, but my guess is also time consuming.
Seems like someone else (Mears?) had a bus service. But the downside was it was a certain pick up time on both ends. And I didn't want to stay that long.
What I have done the last two trips, and will do again next month, is use YourRide. And I have my half hour stop at the Character Corner (where the REAL bargains are anyway). CC is right outside of WDW property and doesn't cost me any extra for the stop.