Prepper Stash: Vespiary
Find this stash by the Grain Elevator in John's Region, well east of Fall's End, and a little north of Zip's place.
When you arrive, you'll see a lone sniper fending off an enemy mob, Grace Armstrong style.
Help him clear out the resitance down below, including one VIP. With the sniper as a distraction, you easily take these guys out with a shot to the back or a blow to the head.
When they've all been pacified, read the note box on some crates out front to start the mission proper.
Follow your marker to a high window, and smash the boards there to enter the building.
Take a left (west) inside. Toward the end of the passage, look up and right (north) for a climb bar.
Crouch, and sneak past the hive.
past that you'll see a passage with a suitcase in a table. Just beyond that table, the floor will collapse under you.
As you land you'll see a safe, You don't need to loot it, but if you want to, you'll have to break the hive here, so make sure you have either the armor, health, or medicine to withstand a bit of stinging. Still, a lot of trouble for $250.
When ready, head west over a blue-roped crate.
Climb some crates to your right, and smash away the slats there.
Climb the stairs and jump across the gap.
Jump another gap (running leap!), then jump across some beams, being careful to to kick the hive.
Jump across the room from the last beam (southwestish), and pull yourself up the climb bar.
Go up the stairs and clamber up one last platform (above the chest), to finally reach the stash.
This unlocks the Gold Medalist skin. You can also loot the area for ammo and the requisite three perk mags. Exit via the zipline when ready.