A taxi to Universal is around $30-$35 for up to 5 people.
For public transportation: Lynx bus goes, you can take Lynx 50 to the downtown bus station, then get on Lynx 40. Bus fair is $1.25 per person, and that includes a free transfer. Kids are only $.50, but there is no transfer for them, so it has to be paid each time they board. The trip will take around 2 hours, depending on trafic conditions, but it is cheap. Just keep in mind you must have EXACT CHANGE because the drivers do not make change. For other information, you can call them at 407-841-LYNX.
Mears is $14 roundtrip per person from Disneyworld hotels to Universal guest drop off. Call Mears for reservation to be picked up at your hotel and then, after park closing, go to guest drop off to be picked up.
Universal can directly book transportation. Call 800-407-4275 option 2. It's called the moviestar shuttle. They require a 12 day advance notice though.