Just back from a quick UO/WDW trip, SEP 2012.
Only had one day for Universal, a Sunday on Labor Day weekend. I figured we would wait to buy the Express Passes. Checking out the crowd level once we were at the park.
We arrived about 11AM, straight from the airport, to find Despicable Me with a 70 minute wait. OK - off to buy the Express Passes! Yes sir, you can buy them here, $69 each...ouch!
Knew the parks would be a bit busy on a holiday weekend, wish I had bought the Passes online, they were $55.
So we overpaid by $28. At least most everything was a walk on, including Forbidden Journey (which does not accept the Express Pass).