Didn't think SuperShuttle did that kind of ripoff - there's another shuttle at DFW that tried to charge me something like that when they didn't have any other pax going toward downtown and offered to "lease" the whole van.

I only take taxis in Asia, and I've never arrived at IAH that late, but Uber and Lyft are becoming quite popular - you may be able to reserve something in advance, as it's done via an app. No personal experience.