You can win and earn amazon codes on get paid to sites, otherwise known as gpt sites. These sites reward members who complete advertiser based tasks. You are rewarded with points and those points can be redeemed for a variety of gift codes and cash. The most popular reward offered is amazon gift card codes, these codes will instantly add money to your amazon acct.
MePrizes.com is a great site to get free amazon gift card codes. You earn them from completing simple tasks that anyone can do.
CaveofWonder.com is a rewards site that offers instant amazon gift card codes as well as paypal cash.
PocketMoneyGPT.com is a fun rewards site with surveys and crowdflower tasks that are easy and fun.
SwagBucks.com is a great place to earn amazon codes. you can earn the codes easily with the search and win as well as the swa tv video area.
GiftHulk.com is like swagbucks, if you lke that site than be sure to join this one. Joining multiple sites will help you earn amazon codes quicker.
InstaGC.com is a great get paid to site that has many ways to earn and win amazon gift codes, they even give them away in the shout box.