I want to sell a second hand item to a friend. We have made up a price that we both agree on. Now I found out that it may be worth much less in the market, although he really likes specifically what I have. Is it a problem to sell it for the agreed price?

One should let the buyer know about the market rate of this second hand item, and if he agrees it is permitted.

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חו״מ רכ״ז סכ״א.