A trader and guards

A trader and guards is a scripted special encounter in Fallout 2. You can find this encounter only in four squares north of Modoc, and walking around a block of two squares in all directions.

Overview
You meet a trader named Willy with some guards. He wants to sell something to you. Problem is, while talking to him you fall asleep, and must then choose if you want to buy a weapon without knowing exactly what it is.

Weapons
What weapons he might be carrying depends on your level:

The script picks one of these weapons at random and then checks to see if you match the level requirement. If the alien blaster was picked you must also pass a Luck check or the result is re-rolled.

The price Willy asks in dialogue is the weapon's usual barter value (excluding ammunition) multiplied by (11-LK), meaning he'll ask $10000 for the alien blaster if you have Luck 10. You may be able to get a better price just by hitting barter.