Shalom Cvod Harav,
Is the following considered underpaying?
I can’t find Cheshbon Hanefesh anywhere at a reasonable price in English but it appeared motzei shabbat for 25 dollars on Ebay. I bought it, but am now wondering if I underpaid. It is available used for around 100 – 125 dollars due to the lack of supply, but I can’t afford to pay that much.
There is no issue of ona’ah here. The reason is because when people sell used items on e-bay, they know that they are merely giving a price, which might be considerably discounted. Similar to when people make garage sales, they just want to get rid of the item, and make a little money on it. Therefore you don’t have to be concerned about this.