You can use Priceline and bid in the Universal zone. I actually got the Sheraton World when I bid in that zone. Many people only pay between $25 and $35 per night!
I would also look into staying on I-Drive. You can take the I-Ride Trolley to Sea World. It costs 75 per ride and runs between Belz and Sea World. I would stay in the area south of San Lake Road. The north part is cluttered and I-Drive traffic can get pretty bad.