NCL does have a bus transfer from IAH, you should be able to find info on the transfer service from the NCL site. We took a stretch limo from IAH to the pier in April for $85 + tip, they did have a town car for a little less. I'll try to find the name of the limo service and get back to you. We spent an extra day in Houston after the cruise so decided to book a rental car through Enterprise for $59.99 + tax for a full size car , ask for the NCL cruise rate. They picked us up at the cruise terminal in a shuttle bus and took us to their office about 10 minutes away, we dropped off at the airport the next day when we flew out.
Enterprise car rental agency
1815 Bayport Blvd.
Seabrook, TX 77586
(281) 474-4466
7:30 am - 6 pm weekdays
9 am - noon on Saturday
closed Sunday
Approximately 10 miles from Laporte