You can use an aftermarket windshield depending on what accessories you have. I believe if you have the ACC or a HUD then you need OEM and it would be best to deal through the dealer since you will need calibrations done.

Even though you get free windshield replacement in Florida, your insurance might tell you they will only pay aftermarket pricing. For my 12 A7 I had to get the windshield replaced last year and went aftermarket with no problems. I don't have ACC or HUD. I went with a company called Glass Doctor as I have dealt with them many times for rock chips and like their work. When I contracted with them they asked about ACC and HUD and were upfront that they would not do the work if I had those options.