We went over to Universal on two separate days on our trip back in December from POP. It came out to be $35 to $37 (without tip) each way.
Our first day, we had called Mears from our room about a half hour early to have a taxi meet us in front of POP, but no one ever showed up. When we asked the cast members up front about the taxi, they said none had shown up but they did have two on-call guys hanging around that morning looking for anyone who needed a ride. The one we took was a plain white transport van with a very similar name on the side, I can't remember if it was Meens or Mearns, or something similar. He was waiting & talking with the concierge but was not affiliated with Mears. Normally, my red flag starts waving of a bait & switch but he was vouched for by cast members and other than his van needing a good cleaning, he had all of his licenses, etc prominently displayed. Looked like a one-man operation. He took us (four people) over to Universal for $36 total and gave us his phone number so he could come back again at the end of the day to take us back to POP ($36 again), which worked out fine. I saw him waiting with the POP cast members at least two other days as well.
The second day, we just walked down to the pick-up area and the concierge hailed a Mears cab that was just sitting around outside. He charged $35 for all four of us as well. The return taxi to POP was about $37, just because we got stuck in rush hour traffic. Our only issue with the Mears Taxis were that while they were equipped with credit card readers, in both instances - neither cab driver could get them to work. I don't know if they were isolated incidents or a common issue.