Galaxy S3, nice device, congratulation for owning it. Maril said right, China is a big market own rich kinds of accessories no matter what digital products. Purchasing on China shopping website is your best choice.
Honor to recommend several my collections for your requirements.
1. Car charger, double USB ports, is enough for using in a car Surely fit Samsung Galaxy S3 car charger - Online shopping for car charger with free shipping at tinydeal.com
2. About the wall charger, sorry I can't find any one though searched for much time. Wall charger needs another replacement battery, not so, you can not using phone when battery is charging. In that case, a battery case is better choice. Except for thicker and heavier, it make your phone last longer, and charging the battery case is simultaneous as standby. Here also have silicon case and pouch alternative, check it out here battery case galaxy s3 - Online shopping for battery case galaxy s3 with free shipping at tinydeal.com
3. Attachment 56179 This car mount fits general PDA and mobile phones, 360° rotating, adjusted for any suitable angle, sucker design, firmly sucked on car glasses. 360° Rotating Universal Car Swivel Mount Holder f Mobile Phone MHD-114225 - TinyDeal. Another dock station, only this I can find that fits SG S3 Portable Charging Dock Station for Samsung Galaxy S3 i9300 MCG-110599 - TinyDeal, no much excellent point but practical.Attachment 56180
Also, screen protector and power bank is necessities. Thanks !