After the PC purchase a container of some sort (backpack, chest, saddle bags, sacks, whatever) they find a signet ring in the container.
A quick heraldry/history/knowledge check will lead them to discover the symbol on the ring is from a long-lost dynasty that vanished in a nearby jungle hundreds of years ago.
The location of the lost dynasty is well known, but only a few of the treasure seekers who have braved the jungle have never returned. None of them found anything other than large insects, poisonous snakes and heartache.
However, there is one person who entered the jungle and returned intact. He’s too old to adventure anymore, but has always wanted to fund an expedition into the jungle to find ruins he just knows are there.