At the time of writing (July 2024) you can buy a used RTX 3090 on eBay for around $700-800. This market resolves YES if at any point during 2025 an RTX 3090 goes for sale or is sold on eBay for less than $300 (shipping cost included). The seller must have at least 10 items sold and at least 95% positive feedback.

Errors made by the seller, like dropping a digit in the price by accident, don't count. The unit has to be sold "in working order", without needing any special attention or modification beyond what a newly produced unit would.