You can get $5 worth of Amazon Coins for $1 by buying the lowest tier of Humble Bundle's
E3 2016 Digital Ticket bundle.
However, you must be in the United States to get the Amazon Coins.
The way this works is you pay what you want, with a minimum of $1. $1 gets you all the items in the first tier, which includes a code for 500 Amazon coins. You'll also get a bunch of other stuff:
- Twitch Turbo 30 Day Subscription
- Psychonauts (Game)
- Mountain (Game)
- Wildstar E3 Pack (PC In-Game Content)
- Warframe PC Booster Pack (PC In-Game Content)
- GUNS UP! Starter Pack + TV Head (PS4 In-Game Content)
- Super Senso Beta Access + Sensonium Pack (Android/iOS Game)
- Armored Warfare E3 Pack (PC In-Game Content)
- Ghost in the Shell: Stand Alone Complex - First Assault Online: Exclusive E3 Digital Ticket Bundle (PC Game/In-Game Content)
- SUPERFIGHT Closed Beta Access + The Joiner Micro Deck (PC Game/In-Game Content)
- Pathfinder Adventures - 40 Chests (Android/iOS In-Game Content)
- Neverwinter Adventurer's Helper Pack + Exclusive Lord of the Labyrinth Title (PC In-Game Content)
There are regional restrictions on some of those things too, not just the Amazon Coins. So if you're outside the US, check the fine print before buying.