Bottom line it will not pay for itself. Do not accept folklore posted here as any sort of science. Use this calculator to see for yourself.
Mobile Insulation Savings Calculator to determine savings by adding or upgrading home insulation. To use this calculator you will need your 'degree days'. You can Google that. It is readily available.
Edit to add: Reflective insulation, foil insulation, has a cooling savings of 3-4% of your cooling bill. That is not your electric bill. It will not pay for itself in your lifetime and your children's lifetime. Let me see if I can find find the studies that reflect that. Or simply Google it or search this forum.