We rent a car for our one day at Universal. I was quoted a price of around $50 ea way for a taxi, and I don't think the shuttle was much cheaper for the 4 of us. You can take the bus service to TTC, and rent from National. YOu can book online at National, and if you join their Emerald Club (free right now) you get a much better price (around $30/day for me for a midsize, including taxes). It's a bit less convenient than a taxi, but saves about $70.