Based on the short story by RL Stevenson.
There’s a bottle containing an imp. Whoever dies whilst possessing it will suffer an eternity of torment. The bottle can only be sold for an exact number of US dollars, in increments of $1, and can only be sold for less than it was purchased for.
The possessor of the bottle will be safe from casual random things that may kill him/her but won’t protect from old age or deliberate reckless behaviour. Whilst possessing the bottle you will live the life of a D&D character with a godlike “Luck” stat. Wealth, prestige, love etc. will come very easily to you, whatever is important to you.
Once the bottle is no longer yours you will not lose the things you have built but subsequent events will be back to your normal level of luck. The “lucky” effect will not help you find a buyer for the bottle. Each buyer needs to fully understand the situation, the veracity of which is fully demonstratable.
How much is the lowest you would you buy the bottle for, and how long before you tried to offload it?