Find the vault with the prize in it, after listening to Festus' speech.
After finding at least 50 Sunset Sarsaparilla star bottle caps, the player can approach Festus to receive the prize, which is, amusingly, the honor of listening to the supposedly real story of how Sunset Sarsaparilla came to be. At this point, the number of star caps exceeding fifty, are simply converted into bottle caps and given back to the player. This course of action fails the preliminary quest, The Legend of the Star.
If you ask about the real prize, Festus tells you that due to legal constraints, the main prize had been removed, and another was being offered that should suffice. This triggers the next and final quest, which instructs you to go to the Sunset Sarsaparilla prize vault to collect your prize.
The final destination is marked inside the factory. To get there, follow these instructions:
Starting from Festus, head through the north door and carry on across the hall to the room with the hole in the roof.
Walk up the wreckage to the 2nd floor.
Take your first left and then right. You should see a very long corridor.
Walk straight to the end of that corridor and you should then be in the room with the hole in the floor.
You'll know you're in the correct room, as it has a wall safe at the back, and a 'Broken Personal Assistant'.
The hole then leads to the prize room.
The real prize turns out to be around 1500 bottle caps, found in thirteen Sunset Sarsaparilla crates, each averaging roughly 115 caps. There are also 319 Sunset Sarsaparilla deputy badges, which are weightless and monetarily worthless (finding them all may require pulling crates off the top shelves). Also, in the corner, lies the body of Allen Marks, a holotape, and Pew Pew, a unique laser pistol. Marks is "wearing" one of the deputy badges, which is actually just lying atop his body (moving the body will cause the badge to fall to the floor). The holotape (which ends the quest when picked up) reveals that he was a murderer and a thief, and a computer found in the bottling area of the building seems to reveal the moment Marks broke into the factory. There are indications that several robots were damaged in the incident, but also that the intruder had been wounded in the process. According to Marks' holotape, the sealed vault was completely airtight, explaining his eventual death after being merely wounded.
Go to the Sunset Sarsaparilla Prize Vault to collect your prize.