Park on any street around the airport

Then call the cab pay him 3-4 dollars and he will take you to the airport

When you are back, call the cab, pay him 3-4 dollars and he will take you to your car which is 4-5 miles away.

Cheapest ever.

Did I ever do this?

No, because never had the time to find such a parking place on a street around IAH. I am sure there is one somewhere there...