On the "man, how did I overlook this?" front . . .
Dustin Brandt stopped blogging over at Fire in the Jungle back in September 2013. Before he signed off, he reduced the price of three, 16-page jungle-themed sandbox adventure tools to $6.54 each. And he made the PDFs available for FREE.
He's using MagCloud, which used to be owned by Hewlett-Packard and is now owned by Blurb. You'll need a free account to download the PDFs. If you want print, you'll have to pony up the cash via credit card or PayPal. Shipping starts at $2.56 for U.S. First Class Mail. For less than $25, you can get three cool jungle adventures delivered in print to your door.
Fire in the Jungle
Across the Wide Dark Jungle
Jungle Castle Rock Apocalypse
Also, be sure to grab his free little fantasy rpg supplement, The Rise and Fall of Zamzer and its accompanying map, which is based on material he wrote back in high school and college.