DIY....
1. Tear newspaper to make templates that fit exactly into the sliding window and rear window. USA Today only, no other newspaper will work.
2. At Autozone get a roll of 95% or 98% window tinting.
3. Using templates from step 1., cut out pieces from the roll of window tint to match windows, ADDING one inch all around.
4. Take the tint cutouts from step 3. to Office Max and laminate them. They're the only office store with a large laminator. The laminator will leave some wrinkles and air bubbles, but this does not affect their effectiveness in an way.
Fairly cheap, and if you lose one just keep the paper template and make more. Needs to be one inch larger than template because once they're folded they lose some size. Also, being slightly larger allows them to stay in the window without other support. Same for the laminating; gives it some stiffness so it will stand up on it's own in the window.
Put them in as soon as I sit down and leave them in until push back. Brings temp down significantly. Back in at cruise. They are no darker than the too-small removeable shade that comes with the plane so you can see though it just as well.
They fit underneath the aircraft-installed shade too, the ones that are light yellow, that don't cover the whole piece of glass so that the sun is always poking you in the eye. These go from frame to frame, no sun gets through.