In your posts, you're mixing several different things: listed price, value, and market price. Listed price is whatever the seller lists at. Value is subjective but we can say it's whatever the buyer thinks it's worth. I think we can agree on that unless you have a different definition of listed price and value. Market price is the actual clearing price to create a transaction.
In your example of the $1k chicken to a starving person, the market price of that chicken between the buyer and seller is $1k. Doesn't matter what other sellers list it at or what buyers think the chicken is worth. One buyer and one seller transacted and created a market price.