You can buy them from the dealer for pretty cheap, with an A8 you need one with all the buttons you have.
99 Chevy Silverado Z71 6" rough country lift/W 35" tires, 4.10 gears, (4.56 soon) S&B CAI and a flowmaster super 44 exhaust.
"Never argue with a fool, they will lower you to their level and beat you with experience." My personal motto.
Position seat as desired. Hold down set button in door and then hold down the #1 memory button at same time until you hear a little click. You should then be good to go. Same with passenger seat. Holds 4 presets for each seat.