The CHEAPEST yet decent hotel near Universal has to be the Motel 6 off of International Drive, on American Way.
Yes, I know, it's a Motel 6, I know what your thinking. But consider a Motel 6, as you would imagine one, *BUT* brand new and clean! This Motel 6 has been opened for about less than a year, so it has yet to go throgugh all the ailments that suffer most cheapy hotels.
It is bare bones, amenities wise (reletivly small room, plain decore, no shampoo or conditioner, non-enclosed closet, and I would probbaly suggest you bring your own towels) but it's in much better shape then you'd find other hotels in the same price range (and even some more expensive stays). Oh right, the price...
...it's only $30.
Thats the price I've been able to get from Orbitz on numerous ocassions, and if you can't you would probably find the regular walk up rate to be no more then $45.
Oh yeah, and it's also only half a mile away from Universal.
-Kevin