I agree with both posters.... The only ride that I'd like to have express when I was there for a week in Jan 2006 was Mummy .... We would like to ride it again and again but the wait time was around 30-45 minutes ...
We are also trying to get prices for them. We called Universal directly, and the rep said the prices won't be posted until after December 1.
As it is the slow season, the prices will likely be $24.99 each
If you get to the parks early (shortly before they open), I can't imagine you'll need express passes in January. We were there early in Thanksgiving week and the crowds didn't really materialize until 11. By then you can be finished with the biggies. The only looong line we waited in was for Pteranadon Flyers (my concession to DD who wasn't tall enough for Doom, Hulk or Dragons).